Page 160 - ICSE Math 4

• If the given me is between 1:00 p.m. and 11:59 p.m., add 12 hours (12:00) to it.
For example, 6:20 p.m. = 0620 hours + 1200 hours = 1820 hours or 18:20

Exercise 12.2

1. Convert the given 24-hour me to 12-hour me.
(a) 1720 hours (b) 0945 hours (c) 1330 hours (d) 2235 hours

(e) 1450 hours (f) 1025 hours (g) 1905 hours (h) 2340 hours

2. Convert the given 12-hour me to 24-hour me.

(a) 6:20 a.m. (b) 4:30 p.m. (c) 1:35 p.m. (d) 8:10 p.m.

(e) 1:05 a.m. (f) 10:55 a.m. (g) 3:25 p.m. (h) 11:10 a.m.

Converting Days to Hours and Vice Versa
1
We know that 1 day = 24 hours or 24 h, so we can write 1 hour = day. Let’s learn how
to convert days to hours and vice versa. 24

Conversion of Days to Hours

 To convert days to hours, we mul ply the days Remember
by 24. 7 days = 1 week
 To convert days and hours to hours, we mul ply 1 leap year = 366 days

the days by 24 and add the hours to it. 1 year = 12 months
= 365 days
Example 1: Convert (a) 9 days (b) 5 days 16 h to hours.

Solu on: (a) 9 days = 9 × 24 h = 216 h
(b) 5 days 16 h = (5 × 24) h + 16 h = 120 h + 16 h = 136 h

Conversion of Hours to Days

 To convert hours to days, we divide the hours by 24.
 To convert hours to days and hours, we divide the hours by 24. Write the quo ent
obtained as days and the remainder obtained as hours.

Example 2: Convert 428 hours to days and hours.
17  days
1
Solu on: We know that 1 h = day 24 428
24 –24
428
Thus, 428 h = days 188
24
–168
So, 428 h = 17 days 20 h.
20  hours

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