NCERT Solutions for Class 4th Maths Chapter 12 How many hours in a day? — In-text Questions

Book page 178 Updated on2026-09-19

Q1.
Look at the picture below. It shows the time spent on different activities by a doctor. Write the number of hours spent on each activity in the space provided.
6:007:008:009:0010:0011:0012:001:002:003:004:005:006:007:008:009:0010:0011:0012:001:002:003:004:005:00Cooks and getsready to goto HospitalStays atHospitalResting timeCookingSpending timewith childrenDinnerand TVSleepsWakes upLeaves forhospitalReacheshospitalLeaves forhomeReacheshome…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs
The doctor’s day drawn as a 24-hour wheel. Each dotted box asks for the number of hours between two marks.
Answer
6:007:008:009:0010:0011:0012:001:002:003:004:005:006:007:008:009:0010:0011:0012:001:002:003:004:005:00Cooks and getsready to goto HospitalStays atHospitalResting timeCookingSpending timewith childrenDinnerand TVSleepsWakes upLeaves forhospitalReacheshospitalLeaves forhomeReacheshome…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs
The doctor’s day drawn as a 24-hour wheel. Each dotted box asks for the number of hours between two marks.

Read the two marks at the ends of each dotted box and count the hours between them.

FromToWhat the doctor doesHours
6 o’clock morning8 o’clock morningCooks and gets ready to go to Hospital2 Hrs
8 o’clock morning9 o’clock morningGoes to the hospital1 Hr
9 o’clock morning4 o’clock eveningStays at Hospital7 Hrs
4 o’clock evening5 o’clock eveningComes back home1 Hr
5 o’clock evening6 o’clock eveningResting time1 Hr
6 o’clock evening7 o’clock eveningCooking1 Hr
7 o’clock evening8 o’clock eveningSpending time with children1 Hr
8 o’clock evening10 o’clock nightDinner and TV2 Hrs
10 o’clock night6 o’clock next morningSleeps8 Hrs
6:007:008:009:0010:0011:0012:001:002:003:004:005:006:007:008:009:0010:0011:0012:001:002:003:004:005:00Cooks and getsready to goto HospitalStays atHospitalResting timeCookingSpending timewith childrenDinnerand TVSleepsWakes upLeaves forhospitalReacheshospitalLeaves forhomeReacheshome2 Hrs1 Hr7 Hrs1 Hr1 Hr1 Hr1 Hr2 Hrs8 Hrs
The same wheel with every dotted box filled in.
2 + 1 + 7 + 1 + 1 + 1 + 1 + 2 + 8 = 24 Hrs
Why it happens: Between two marks on the wheel you simply count the hour steps, the same way you count steps on a number line.
Tip: In the picture the shaded band marked Stays at Hospital reaches up to 5 o’clock, but the mark Leaves for home is placed at 4 o’clock. Count from the marks: 7 hours at the hospital and 1 hour on the way home.
Q2.
Then, find the total number of hours between 6 o’clock morning to 6 o’clock evening and 6 o’clock morning of the next day. The total number of hours is ________ .
6:007:008:009:0010:0011:0012:001:002:003:004:005:006:007:008:009:0010:0011:0012:001:002:003:004:005:00Cooks and getsready to goto HospitalStays atHospitalResting timeCookingSpending timewith childrenDinnerand TVSleepsWakes upLeaves forhospitalReacheshospitalLeaves forhomeReacheshome…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs
The doctor’s day drawn as a 24-hour wheel. Each dotted box asks for the number of hours between two marks.
Answer
6:007:008:009:0010:0011:0012:001:002:003:004:005:006:007:008:009:0010:0011:0012:001:002:003:004:005:00Cooks and getsready to goto HospitalStays atHospitalResting timeCookingSpending timewith childrenDinnerand TVSleepsWakes upLeaves forhospitalReacheshospitalLeaves forhomeReacheshome…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs…… Hrs
The doctor’s day drawn as a 24-hour wheel. Each dotted box asks for the number of hours between two marks.

Count the two halves of the wheel one after the other.

6 o’clock morning → 6 o’clock evening = 12 hours
6 o’clock evening → 6 o’clock next morning = 12 hours
12 + 12 = 24 hours

The total number of hours is 24.

Check it yourself: Add up the nine parts of the doctor’s day: 2 + 1 + 7 + 1 + 1 + 1 + 1 + 2 + 8 = 24. The same answer.
Why it happens: A clock face shows only 12 hours. In one full day the hour hand goes round it twice, so a day has 12 + 12 = 24 hours.
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