Page 136 - Maths Class 05
P. 136
Converting hours into minutes
Example : Convert 9 hours into minutes.
Solution : 1 hour = 60 minutes
9 hours = 9 × 60 minutes
= 540 minutes
1
7
Example : Convert hours into minutes.
2
Solution : 1 hour = 60 minutes
7 hours = 7 × 60 minutes = 420 minutes
1
hours = 30 minutes
2
1
7 hours = 420 + 30 minutes = 450 minutes
2
Converting seconds into minutes
Example : Convert 2160 seconds into minutes. 3 6 ® minutes
60 2 1 6 0
1
Solution : 1 second = minutes – 1 8 0
60
3 6 0
2160
2160 seconds = minutes – 3 6 0
60
0
= 36 minutes
Converting minutes into hours
Example : Convert 240 minutes into hours.
4 ® hours
1
Solution : 1 minute = hours 60 2 4 0
60
– 2 4 0
240
240 minutes = hours 0
60
= 4 hours
Addition of hours, minutes and seconds (without carry over)
Example : Add 9 hours 42 minutes 30 seconds and 18 hours 12 minutes 18 seconds.
Solution : Step 1 : Write hours, minutes and seconds columnwise.
Step 2 : Add the seconds column first.
30 seconds + 18 seconds
= 48 seconds
Mathematics-5 136
