Page 174 - ICSE Math 5

= (24 h + 1 h) + 53 min + 12 s (since 60 min = 1 h)
= 25 h + 53 min + 12 s

So, 24 h 112 min 72 s = 25 h 53 min 12 s.
Example 10: Divide 25 h 55 min 27 s by 3.

Solution: Step 1: Convert the given hours and minutes to seconds.
25 h = 25 × 60 min = 1,500 min (since 1 h = 60 min)

 1,500 min = 1,500 × 60 s = 90,000 s (since 1 min = 60 s)
55 min = 55 × 60 s = 3,300 s

Step 2: Add 90,000 s and 3,300 s to 27 s.
90,000 s + 3,300 s + 27 s = 93,327 s
3 1 1 0 9
Step 3: Now divide 93,327 s by 3. 3 9 3 3 2 7
93,327 s  3 = 31,109 s – 9
0 3
Step 4: Convert 31,109 s to h, min and s.
– 3
31,109
31,109 s to min = min = 518 min 29 s 0 3
60
– 3
518
518 min to h = h = 8 h 38 min 0 2
60
– 0
So, 31,109 s = 8 h 38 min 29 s.
2 7
– 2 7
Calculation
0 0
5 1 8 min 8 h
60 3 1 1 0 9 60 5 1 8
– 3 0 0 – 4 8 0
1 1 0 3 8 min
– 6 0
5 0 9
– 4 8 0
2 9 s

Word Problems

Let's solve the given word problem.
Example 11: An Indian Airlines flight departs from Mumbai at 3:50 p.m. The flight takes 1 hour

15 minutes to reach Goa. At what time will it reach Goa?
Solution: Time of departure of flight from Mumbai = 3:50 p.m., i.e., 15 hours 50 minutes

Time taken by the flight to reach Goa = 1 hour 15 minutes
 Time of arrival of flight in Goa = 15 hours 50 minutes + 1 hour 15 minutes

= 17 hours 5 minutes

So, the flight will reach Goa at 5:05 p.m.

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