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132 Maths

Step 2: We are left with 28 min. Now, 28 – 35 is not possible. So we borrow 1
hour = 60 min from hour column.

60 min + 28 min = 88 min
88 min – 35 min = 53 min

Step 3: (4 – 2) h = 2 h
Hence, the difference is 2 h 53 min 41s.

Example 3: Add 7 weeks 5 days and 8 weeks 4 days. Weeks Days
Solution: Step 1: 5 days + 4 days = 9 days 1

= 7 days + 2 days 7 5

= 1 week + 2 days + 8 4
Carry 1 week to weeks column and write 2 as days. 16 2

Step 2: Add (1 + 7 + 8) weeks = 16 weeks
Hence, the required sum is 16 weeks 2 days.

Exercise 10.2

1. Add the following.

(a) 1 min 30 s and 45 s (b) 4 h 22 min 30 s and 3 h 21 min 45 s
(c) 3 h 47 min and 57 min (d) 2 days 17 hours and 3 days 12 hours

(e) 5 weeks 5 days and 4 weeks 6 days
2. Subtract the following.
(a) 3 h 34 min from 5 h 55 min (b) 35 min 45 s from 43 min 10 s

(c) 6 h 25 min from 8 h 50 min (d) 3 days 12 h from 5 days 21 h
(e) 3 weeks 5 days from 7 weeks 3 days

3. Subtract 15 years 9 months from 21 years.
4. What time will it be 3 hours 20 min after 7:30 p.m.?

5. Find the time interval between 7:25 a.m. and 4:10 p.m.

Duration of Time (in Hours/in Days)

The 24-hour time notation is represented by a Challenge
‘24-hour clock’. Here, the time from 12 midnight to I’m always moving, never still,
next 12 midnight (1 day) is given as: 00:00 hours to You can’t touch me,
24:00 hours, where the first two digits refer to hours but you feel my thrill.
and the last two to minutes. I measure days, months, and years,

Sometimes bringing joy, sometimes tears.
I’m goes up but never comes down?
What am I?