Page 130 - Math Skill - 4

128 Maths

Addition and Subtraction of Time
Let us learn addition and subtraction of time through examples.

Let’s Attempt
h min
Example 1: Add 6 hours 30 minutes and 2 hours 40 minutes. 1
Solution: Write hours and minutes in separate columns. 6 3 0
Step 1: Add minutes; 30 + 40 = 70 minutes + 2 4 0

70 min = 1 hour 10 minutes 9 1 0
So, write 10 in minutes column and carry 1 to hours column
Step 2: Add hours; 1 (carried over) + 6 + 2 = 9 hours

Thus, the required sum = 9 hours 10 minutes.
Example 2: Subtract 4 h 45 min from 7 h 26 min.
Solution: Step 1: Subtract minutes; 45 min cannot be subtracted from 26 min.
Borrow 1 h (60 min) from 7 hours. h min

60 min + 26 min = 86 min 6 8 6
Now, 86 min – 45 min = 41 min 7 2 6
Step 2: Subtract hours; 6 h – 4 h = 2 h – 4 4 5

Thus, the required difference is 2h 41 min. 2 4 1
Example 3: A movie took 2 hours 40 minutes to finish. During the show, interval took 15
minutes. Find out the actual time duration of the movie.

Solution: Total time duration of the movie = 2 h 40 min h min
Time of interval = 15 min 3 10
Actual time duration of movie = 2 h 40 min – 15 min 2 4 0

= 2 h 25 min – 0 1 5
2 2 5

Exercise 9.7

1. Add the following.
(a) 7 hours 15 minutes and 3 hours 35 minutes
(b) 10 h 39 min and 7 h 40 min (c) 9 h 9 min and 2 h 50 min
2. Subtract the following.

(a) 3 h 43 min from 7 h 50 min (b) 9 h 36 min from 14 h 18 min
(c) 6 h 20 min from 10 h 30 min (d) 30 h from 45 h 15 min
3. An annual day programme got over at 7:30 p.m. If it was of 3 hours duration, when did it

start?
4. Pratima studied English for 1 h 15 min and then she studied Mathematics for 1 h 25 min.
How long did she study?