EN हिं

NCERT Solutions for Class 5th Maths Chapter 12 Adding up times, and finding how long a journey took — Let Us Do (continued)

Book page 162 Updated on2026-09-19

Q2.
Raghav studies Mathematics, English, Hindi, and The World Around Us subjects. He took 50 minutes to study each of the subjects. Find the total time taken in hours and minutes. Share your strategies with your class.
Answer

Raghav studied for 3 hours 20 minutes in all.

What we must find: the total time for four subjects, when each subject took 50 minutes.

  1. Count the subjects. Mathematics, English, Hindi, The World Around Us — that is 4 subjects.
  2. Find the total in minutes. Four lots of 50 minutes: 50 × 4 = 200 minutes.
  3. Change 200 minutes into hours. Count 60s: 60, 120, 180. The next one, 240, is too big. So there are 3 whole hours.
  4. Find the leftover: 200 − 180 = 20 minutes.
  5. Write the answer with both units: 3 hours 20 minutes.
Time for one subject = 50 minutes
Number of subjects = 4
Total = 50 × 4 = 200 minutes
200 = 180 + 20 = (3 × 60) + 20
Total time = 3 hours 20 minutes

Sample answer for ‘share your strategies’: I did not multiply at first. I added in pairs, because 50 + 50 is easy. 50 + 50 = 100 minutes for two subjects. Another 50 + 50 = 100 minutes for the other two. 100 + 100 = 200 minutes altogether. Then I took out hours 60 at a time until only 20 minutes were left.

Another neat strategy: 50 minutes is 10 minutes short of an hour. Four subjects would be 4 hours if each took a full hour. But each is short by 10 minutes, so altogether we are short by 4 × 10 = 40 minutes. 4 hours − 40 minutes = 3 hours 20 minutes. Same answer, and no big multiplication at all.
Check it yourself: 3 hours 20 minutes = 180 + 20 = 200 minutes, and 200 ÷ 50 = 4 subjects ✓
Q3.
Raghu left his house at 08:00 hours and arrived at his Nana ji’s house at 09:05 hours. How long did he take to reach his house?
Answer

Raghu took 1 hour 5 minutes.

The book shows the neat way to do this — jump forward in easy hops instead of writing a subtraction sum.

  1. Hop 1 — to the next full hour. 08:00 hours to 09:00 hours is 1 hour.
  2. Hop 2 — the leftover minutes. 09:00 hours to 09:05 hours is 5 minutes.
  3. Add the hops. 1 hour + 5 minutes = 1 hour 5 minutes.
08:00 → 09:00 = 1 hour
09:00 → 09:05 = 5 minutes
Time taken = 1 hour 5 minutes
Why not just do 09:05 − 08:00 in columns? Here it happens to work, because 5 minutes is more than 0 minutes. But if he had arrived at 08:55 and left at 08:00 you would be fine, while a start of 08:40 and an arrival of 09:05 would need borrowing — and time borrows 60, not 10. Hopping forward never runs into that trouble.
In minutes: 1 hour 5 minutes = 60 + 5 = 65 minutes. Note also that these are 24-hour format times, so 08:00 hours means 8 o'clock in the morning.
Was this helpful?