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Find the rule of changing clock times · 10 practice problems

2.MD.C.7

Generated variants — 10

Freshly produced from the archetype’s parameters — problem, figure, and solution derived together.

Variant 1 answer: 5:20

The clocks change according to a fixed rule. Find the rule for how the clocks change, then find the time shown on the last clock.

Five clock faces are placed in a row from left to right, joined by arrows. The first shows 3:203{:}20, the second shows 3:503{:}50, the third shows 4:204{:}20, the fourth shows 4:504{:}50. Find the time shown on the fifth (last) clock.

3:20 3:50 4:20 4:50 ?
Show solution

Understand

Five clocks in a row change by a fixed rule. From the first 4 times, find the rule and use it to find the time on the fifth clock.

Givens
  • Clock 1 shows 3:20.
  • Clock 2 shows 3:50.
  • Clock 3 shows 4:20.
  • Clock 4 shows 4:50.
Unknowns
  • The time shown on the fifth (last) clock.
Constraints
  • The same time change is applied from each clock to the next.
  • 60 minutes make 1 hour, so minutes past 60 roll over to the next hour.

Plan

#5 Look for a Pattern · also uses: #8 Analyze the Units

The times form a sequence, so I find how much time is added at each step (the pattern), then add that same amount to the last shown time, watching the minute-to-hour rollover (units).

Execute

#5 Look for a Pattern 2.MD.C.7
Comparing each clock to the next, the same jump of +30 minutes happens every time. So the rule is: add 30 minutes each time.
3:20+303:50+304:20+304:503{:}20 \xrightarrow{+30} 3{:}50 \xrightarrow{+30} 4{:}20 \xrightarrow{+30} 4{:}50
Reading each clock and comparing tells you the steady jump.
#8 Analyze the Units 2.MD.C.7
Add 30 minutes to 4:50. Since 50 + 30 = 80 minutes, that is 1 hour past the hour with 20 minutes left, so 4:50 becomes 5:20.
4:50+30 min=5:204{:}50 + 30\text{ min} = 5{:}20
When the minutes pass 60 you carry one hour, just like carrying in place value.
Answer: 5:20

Review

Each step adds 30 minutes, and 5:20 continues that pattern from 4:50, so the answer fits the sequence.

Add up the total change: 4 steps of 30 minutes from 3:20 lands on the same time, 5:20.

Standards · min grade 2

  • 2.MD.C.7 Tell and write time from analog and digital clocks to nearest five minutes — Reading the clock times and adding the fixed step including the hour rollover.
💡 Each clock jumps 30 minutes, and when minutes pass 60 you just bump up one hour!
Variant 2 answer: 7:00

The clocks change according to a fixed rule. Find the rule for how the clocks change, then find the time shown on the last clock.

Five clock faces are placed in a row from left to right, joined by arrows. The first shows 6:406{:}40, the second shows 6:456{:}45, the third shows 6:506{:}50, the fourth shows 6:556{:}55. Find the time shown on the fifth (last) clock.

6:40 6:45 6:50 6:55 ?
Show solution

Understand

Five clocks in a row change by a fixed rule. From the first 4 times, find the rule and use it to find the time on the fifth clock.

Givens
  • Clock 1 shows 6:40.
  • Clock 2 shows 6:45.
  • Clock 3 shows 6:50.
  • Clock 4 shows 6:55.
Unknowns
  • The time shown on the fifth (last) clock.
Constraints
  • The same time change is applied from each clock to the next.
  • 60 minutes make 1 hour, so minutes past 60 roll over to the next hour.

Plan

#5 Look for a Pattern · also uses: #8 Analyze the Units

The times form a sequence, so I find how much time is added at each step (the pattern), then add that same amount to the last shown time, watching the minute-to-hour rollover (units).

Execute

#5 Look for a Pattern 2.MD.C.7
Comparing each clock to the next, the same jump of +5 minutes happens every time. So the rule is: add 5 minutes each time.
6:40+56:45+56:50+56:556{:}40 \xrightarrow{+5} 6{:}45 \xrightarrow{+5} 6{:}50 \xrightarrow{+5} 6{:}55
Reading each clock and comparing tells you the steady jump.
#8 Analyze the Units 2.MD.C.7
Add 5 minutes to 6:55. Since 55 + 5 = 60 minutes, that is 1 hour past the hour with 0 minutes left, so 6:55 becomes 7:00.
6:55+5 min=7:006{:}55 + 5\text{ min} = 7{:}00
When the minutes pass 60 you carry one hour, just like carrying in place value.
Answer: 7:00

Review

Each step adds 5 minutes, and 7:00 continues that pattern from 6:55, so the answer fits the sequence.

Add up the total change: 4 steps of 5 minutes from 6:40 lands on the same time, 7:00.

Standards · min grade 2

  • 2.MD.C.7 Tell and write time from analog and digital clocks to nearest five minutes — Reading the clock times and adding the fixed step including the hour rollover.
💡 Each clock jumps 5 minutes, and when minutes pass 60 you just bump up one hour!
Variant 3 answer: 2:00

The clocks change according to a fixed rule. Find the rule for how the clocks change, then find the time shown on the last clock.

Four clock faces are placed in a row from left to right, joined by arrows. The first shows 12:1512{:}15, the second shows 12:5012{:}50, the third shows 1:251{:}25. Find the time shown on the fourth (last) clock.

12:15 12:50 1:25 ?
Show solution

Understand

Four clocks in a row change by a fixed rule. From the first 3 times, find the rule and use it to find the time on the fourth clock.

Givens
  • Clock 1 shows 12:15.
  • Clock 2 shows 12:50.
  • Clock 3 shows 1:25.
Unknowns
  • The time shown on the fourth (last) clock.
Constraints
  • The same time change is applied from each clock to the next.
  • 60 minutes make 1 hour, so minutes past 60 roll over to the next hour.

Plan

#5 Look for a Pattern · also uses: #8 Analyze the Units

The times form a sequence, so I find how much time is added at each step (the pattern), then add that same amount to the last shown time, watching the minute-to-hour rollover (units).

Execute

#5 Look for a Pattern 2.MD.C.7
Comparing each clock to the next, the same jump of +35 minutes happens every time. So the rule is: add 35 minutes each time.
12:15+3512:50+351:2512{:}15 \xrightarrow{+35} 12{:}50 \xrightarrow{+35} 1{:}25
Reading each clock and comparing tells you the steady jump.
#8 Analyze the Units 2.MD.C.7
Add 35 minutes to 1:25. Since 25 + 35 = 60 minutes, that is 1 hour past the hour with 0 minutes left, so 1:25 becomes 2:00.
1:25+35 min=2:001{:}25 + 35\text{ min} = 2{:}00
When the minutes pass 60 you carry one hour, just like carrying in place value.
Answer: 2:00

Review

Each step adds 35 minutes, and 2:00 continues that pattern from 1:25, so the answer fits the sequence.

Add up the total change: 3 steps of 35 minutes from 12:15 lands on the same time, 2:00.

Standards · min grade 2

  • 2.MD.C.7 Tell and write time from analog and digital clocks to nearest five minutes — Reading the clock times and adding the fixed step including the hour rollover.
💡 Each clock jumps 35 minutes, and when minutes pass 60 you just bump up one hour!
Variant 4 answer: 12:30

The clocks change according to a fixed rule. Find the rule for how the clocks change, then find the time shown on the last clock.

Five clock faces are placed in a row from left to right, joined by arrows. The first shows 9:309{:}30, the second shows 10:1510{:}15, the third shows 11:0011{:}00, the fourth shows 11:4511{:}45. Find the time shown on the fifth (last) clock.

9:30 10:15 11:00 11:45 ?
Show solution

Understand

Five clocks in a row change by a fixed rule. From the first 4 times, find the rule and use it to find the time on the fifth clock.

Givens
  • Clock 1 shows 9:30.
  • Clock 2 shows 10:15.
  • Clock 3 shows 11:00.
  • Clock 4 shows 11:45.
Unknowns
  • The time shown on the fifth (last) clock.
Constraints
  • The same time change is applied from each clock to the next.
  • 60 minutes make 1 hour, so minutes past 60 roll over to the next hour.

Plan

#5 Look for a Pattern · also uses: #8 Analyze the Units

The times form a sequence, so I find how much time is added at each step (the pattern), then add that same amount to the last shown time, watching the minute-to-hour rollover (units).

Execute

#5 Look for a Pattern 2.MD.C.7
Comparing each clock to the next, the same jump of +45 minutes happens every time. So the rule is: add 45 minutes each time.
9:30+4510:15+4511:00+4511:459{:}30 \xrightarrow{+45} 10{:}15 \xrightarrow{+45} 11{:}00 \xrightarrow{+45} 11{:}45
Reading each clock and comparing tells you the steady jump.
#8 Analyze the Units 2.MD.C.7
Add 45 minutes to 11:45. Since 45 + 45 = 90 minutes, that is 1 hour past the hour with 30 minutes left, so 11:45 becomes 12:30.
11:45+45 min=12:3011{:}45 + 45\text{ min} = 12{:}30
When the minutes pass 60 you carry one hour, just like carrying in place value.
Answer: 12:30

Review

Each step adds 45 minutes, and 12:30 continues that pattern from 11:45, so the answer fits the sequence.

Add up the total change: 4 steps of 45 minutes from 9:30 lands on the same time, 12:30.

Standards · min grade 2

  • 2.MD.C.7 Tell and write time from analog and digital clocks to nearest five minutes — Reading the clock times and adding the fixed step including the hour rollover.
💡 Each clock jumps 45 minutes, and when minutes pass 60 you just bump up one hour!
Variant 5 answer: 7:55

The clocks change according to a fixed rule. Find the rule for how the clocks change, then find the time shown on the last clock.

Six clock faces are placed in a row from left to right, joined by arrows. The first shows 7:057{:}05, the second shows 7:157{:}15, the third shows 7:257{:}25, the fourth shows 7:357{:}35, the fifth shows 7:457{:}45. Find the time shown on the sixth (last) clock.

7:05 7:15 7:25 7:35 7:45 ?
Show solution

Understand

Six clocks in a row change by a fixed rule. From the first 5 times, find the rule and use it to find the time on the sixth clock.

Givens
  • Clock 1 shows 7:05.
  • Clock 2 shows 7:15.
  • Clock 3 shows 7:25.
  • Clock 4 shows 7:35.
  • Clock 5 shows 7:45.
Unknowns
  • The time shown on the sixth (last) clock.
Constraints
  • The same time change is applied from each clock to the next.
  • 60 minutes make 1 hour, so minutes past 60 roll over to the next hour.

Plan

#5 Look for a Pattern · also uses: #8 Analyze the Units

The times form a sequence, so I find how much time is added at each step (the pattern), then add that same amount to the last shown time, watching the minute-to-hour rollover (units).

Execute

#5 Look for a Pattern 2.MD.C.7
Comparing each clock to the next, the same jump of +10 minutes happens every time. So the rule is: add 10 minutes each time.
7:05+107:15+107:25+107:35+107:457{:}05 \xrightarrow{+10} 7{:}15 \xrightarrow{+10} 7{:}25 \xrightarrow{+10} 7{:}35 \xrightarrow{+10} 7{:}45
Reading each clock and comparing tells you the steady jump.
#8 Analyze the Units 2.MD.C.7
Add 10 minutes to 7:45. Since 45 + 10 = 55 minutes (still under 60), the hour stays the same, so 7:45 becomes 7:55.
7:45+10 min=7:557{:}45 + 10\text{ min} = 7{:}55
When the minutes pass 60 you carry one hour, just like carrying in place value.
Answer: 7:55

Review

Each step adds 10 minutes, and 7:55 continues that pattern from 7:45, so the answer fits the sequence.

Add up the total change: 5 steps of 10 minutes from 7:05 lands on the same time, 7:55.

Standards · min grade 2

  • 2.MD.C.7 Tell and write time from analog and digital clocks to nearest five minutes — Reading the clock times and adding the fixed step including the hour rollover.
💡 Each clock jumps 10 minutes, and when minutes pass 60 you just bump up one hour!
Variant 6 answer: 2:00

The clocks change according to a fixed rule. Find the rule for how the clocks change, then find the time shown on the last clock.

Five clock faces are placed in a row from left to right, joined by arrows. The first shows 1:001{:}00, the second shows 1:151{:}15, the third shows 1:301{:}30, the fourth shows 1:451{:}45. Find the time shown on the fifth (last) clock.

1:00 1:15 1:30 1:45 ?
Show solution

Understand

Five clocks in a row change by a fixed rule. From the first 4 times, find the rule and use it to find the time on the fifth clock.

Givens
  • Clock 1 shows 1:00.
  • Clock 2 shows 1:15.
  • Clock 3 shows 1:30.
  • Clock 4 shows 1:45.
Unknowns
  • The time shown on the fifth (last) clock.
Constraints
  • The same time change is applied from each clock to the next.
  • 60 minutes make 1 hour, so minutes past 60 roll over to the next hour.

Plan

#5 Look for a Pattern · also uses: #8 Analyze the Units

The times form a sequence, so I find how much time is added at each step (the pattern), then add that same amount to the last shown time, watching the minute-to-hour rollover (units).

Execute

#5 Look for a Pattern 2.MD.C.7
Comparing each clock to the next, the same jump of +15 minutes happens every time. So the rule is: add 15 minutes each time.
1:00+151:15+151:30+151:451{:}00 \xrightarrow{+15} 1{:}15 \xrightarrow{+15} 1{:}30 \xrightarrow{+15} 1{:}45
Reading each clock and comparing tells you the steady jump.
#8 Analyze the Units 2.MD.C.7
Add 15 minutes to 1:45. Since 45 + 15 = 60 minutes, that is 1 hour past the hour with 0 minutes left, so 1:45 becomes 2:00.
1:45+15 min=2:001{:}45 + 15\text{ min} = 2{:}00
When the minutes pass 60 you carry one hour, just like carrying in place value.
Answer: 2:00

Review

Each step adds 15 minutes, and 2:00 continues that pattern from 1:45, so the answer fits the sequence.

Add up the total change: 4 steps of 15 minutes from 1:00 lands on the same time, 2:00.

Standards · min grade 2

  • 2.MD.C.7 Tell and write time from analog and digital clocks to nearest five minutes — Reading the clock times and adding the fixed step including the hour rollover.
💡 Each clock jumps 15 minutes, and when minutes pass 60 you just bump up one hour!
Variant 7 answer: 12:40

The clocks change according to a fixed rule. Find the rule for how the clocks change, then find the time shown on the last clock.

Three clock faces are placed in a row from left to right, joined by arrows. The first shows 11:5011{:}50, the second shows 12:1512{:}15. Find the time shown on the third (last) clock.

11:50 12:15 ?
Show solution

Understand

Three clocks in a row change by a fixed rule. From the first 2 times, find the rule and use it to find the time on the third clock.

Givens
  • Clock 1 shows 11:50.
  • Clock 2 shows 12:15.
Unknowns
  • The time shown on the third (last) clock.
Constraints
  • The same time change is applied from each clock to the next.
  • 60 minutes make 1 hour, so minutes past 60 roll over to the next hour.

Plan

#5 Look for a Pattern · also uses: #8 Analyze the Units

The times form a sequence, so I find how much time is added at each step (the pattern), then add that same amount to the last shown time, watching the minute-to-hour rollover (units).

Execute

#5 Look for a Pattern 2.MD.C.7
Comparing each clock to the next, the same jump of +25 minutes happens every time. So the rule is: add 25 minutes each time.
11:50+2512:1511{:}50 \xrightarrow{+25} 12{:}15
Reading each clock and comparing tells you the steady jump.
#8 Analyze the Units 2.MD.C.7
Add 25 minutes to 12:15. Since 15 + 25 = 40 minutes (still under 60), the hour stays the same, so 12:15 becomes 12:40.
12:15+25 min=12:4012{:}15 + 25\text{ min} = 12{:}40
When the minutes pass 60 you carry one hour, just like carrying in place value.
Answer: 12:40

Review

Each step adds 25 minutes, and 12:40 continues that pattern from 12:15, so the answer fits the sequence.

Add up the total change: 2 steps of 25 minutes from 11:50 lands on the same time, 12:40.

Standards · min grade 2

  • 2.MD.C.7 Tell and write time from analog and digital clocks to nearest five minutes — Reading the clock times and adding the fixed step including the hour rollover.
💡 Each clock jumps 25 minutes, and when minutes pass 60 you just bump up one hour!
Variant 8 answer: 3:10

The clocks change according to a fixed rule. Find the rule for how the clocks change, then find the time shown on the last clock.

Four clock faces are placed in a row from left to right, joined by arrows. The first shows 2:102{:}10, the second shows 2:302{:}30, the third shows 2:502{:}50. Find the time shown on the fourth (last) clock.

2:10 2:30 2:50 ?
Show solution

Understand

Four clocks in a row change by a fixed rule. From the first 3 times, find the rule and use it to find the time on the fourth clock.

Givens
  • Clock 1 shows 2:10.
  • Clock 2 shows 2:30.
  • Clock 3 shows 2:50.
Unknowns
  • The time shown on the fourth (last) clock.
Constraints
  • The same time change is applied from each clock to the next.
  • 60 minutes make 1 hour, so minutes past 60 roll over to the next hour.

Plan

#5 Look for a Pattern · also uses: #8 Analyze the Units

The times form a sequence, so I find how much time is added at each step (the pattern), then add that same amount to the last shown time, watching the minute-to-hour rollover (units).

Execute

#5 Look for a Pattern 2.MD.C.7
Comparing each clock to the next, the same jump of +20 minutes happens every time. So the rule is: add 20 minutes each time.
2:10+202:30+202:502{:}10 \xrightarrow{+20} 2{:}30 \xrightarrow{+20} 2{:}50
Reading each clock and comparing tells you the steady jump.
#8 Analyze the Units 2.MD.C.7
Add 20 minutes to 2:50. Since 50 + 20 = 70 minutes, that is 1 hour past the hour with 10 minutes left, so 2:50 becomes 3:10.
2:50+20 min=3:102{:}50 + 20\text{ min} = 3{:}10
When the minutes pass 60 you carry one hour, just like carrying in place value.
Answer: 3:10

Review

Each step adds 20 minutes, and 3:10 continues that pattern from 2:50, so the answer fits the sequence.

Add up the total change: 3 steps of 20 minutes from 2:10 lands on the same time, 3:10.

Standards · min grade 2

  • 2.MD.C.7 Tell and write time from analog and digital clocks to nearest five minutes — Reading the clock times and adding the fixed step including the hour rollover.
💡 Each clock jumps 20 minutes, and when minutes pass 60 you just bump up one hour!
Variant 9 answer: 7:15

The clocks change according to a fixed rule. Find the rule for how the clocks change, then find the time shown on the last clock.

Four clock faces are placed in a row from left to right, joined by arrows. The first shows 5:455{:}45, the second shows 6:156{:}15, the third shows 6:456{:}45. Find the time shown on the fourth (last) clock.

5:45 6:15 6:45 ?
Show solution

Understand

Four clocks in a row change by a fixed rule. From the first 3 times, find the rule and use it to find the time on the fourth clock.

Givens
  • Clock 1 shows 5:45.
  • Clock 2 shows 6:15.
  • Clock 3 shows 6:45.
Unknowns
  • The time shown on the fourth (last) clock.
Constraints
  • The same time change is applied from each clock to the next.
  • 60 minutes make 1 hour, so minutes past 60 roll over to the next hour.

Plan

#5 Look for a Pattern · also uses: #8 Analyze the Units

The times form a sequence, so I find how much time is added at each step (the pattern), then add that same amount to the last shown time, watching the minute-to-hour rollover (units).

Execute

#5 Look for a Pattern 2.MD.C.7
Comparing each clock to the next, the same jump of +30 minutes happens every time. So the rule is: add 30 minutes each time.
5:45+306:15+306:455{:}45 \xrightarrow{+30} 6{:}15 \xrightarrow{+30} 6{:}45
Reading each clock and comparing tells you the steady jump.
#8 Analyze the Units 2.MD.C.7
Add 30 minutes to 6:45. Since 45 + 30 = 75 minutes, that is 1 hour past the hour with 15 minutes left, so 6:45 becomes 7:15.
6:45+30 min=7:156{:}45 + 30\text{ min} = 7{:}15
When the minutes pass 60 you carry one hour, just like carrying in place value.
Answer: 7:15

Review

Each step adds 30 minutes, and 7:15 continues that pattern from 6:45, so the answer fits the sequence.

Add up the total change: 3 steps of 30 minutes from 5:45 lands on the same time, 7:15.

Standards · min grade 2

  • 2.MD.C.7 Tell and write time from analog and digital clocks to nearest five minutes — Reading the clock times and adding the fixed step including the hour rollover.
💡 Each clock jumps 30 minutes, and when minutes pass 60 you just bump up one hour!
Variant 10 answer: 6:05

The clocks change according to a fixed rule. Find the rule for how the clocks change, then find the time shown on the last clock.

Three clock faces are placed in a row from left to right, joined by arrows. The first shows 4:254{:}25, the second shows 5:155{:}15. Find the time shown on the third (last) clock.

4:25 5:15 ?
Show solution

Understand

Three clocks in a row change by a fixed rule. From the first 2 times, find the rule and use it to find the time on the third clock.

Givens
  • Clock 1 shows 4:25.
  • Clock 2 shows 5:15.
Unknowns
  • The time shown on the third (last) clock.
Constraints
  • The same time change is applied from each clock to the next.
  • 60 minutes make 1 hour, so minutes past 60 roll over to the next hour.

Plan

#5 Look for a Pattern · also uses: #8 Analyze the Units

The times form a sequence, so I find how much time is added at each step (the pattern), then add that same amount to the last shown time, watching the minute-to-hour rollover (units).

Execute

#5 Look for a Pattern 2.MD.C.7
Comparing each clock to the next, the same jump of +50 minutes happens every time. So the rule is: add 50 minutes each time.
4:25+505:154{:}25 \xrightarrow{+50} 5{:}15
Reading each clock and comparing tells you the steady jump.
#8 Analyze the Units 2.MD.C.7
Add 50 minutes to 5:15. Since 15 + 50 = 65 minutes, that is 1 hour past the hour with 5 minutes left, so 5:15 becomes 6:05.
5:15+50 min=6:055{:}15 + 50\text{ min} = 6{:}05
When the minutes pass 60 you carry one hour, just like carrying in place value.
Answer: 6:05

Review

Each step adds 50 minutes, and 6:05 continues that pattern from 5:15, so the answer fits the sequence.

Add up the total change: 2 steps of 50 minutes from 4:25 lands on the same time, 6:05.

Standards · min grade 2

  • 2.MD.C.7 Tell and write time from analog and digital clocks to nearest five minutes — Reading the clock times and adding the fixed step including the hour rollover.
💡 Each clock jumps 50 minutes, and when minutes pass 60 you just bump up one hour!