You should know that there are:
60 seconds in 1 minute
60 minutes in 1 hour.
This means that there are:
30 seconds in ½ minute
15 seconds in ¼ minute
45 seconds in ¾ minute
30 minutes in ½ hour
15 minutes in ¼ hour
45 minutes in ¾ hour.
Example 1
Jack takes 5¼ minutes to learn his capital cities.
How many seconds is this?
Answer
1 minute = 60 seconds.
½ minute = 30 seconds.
¼ minute = 15 seconds.
5¼ minutes = 5 × 60 + 15 = 300 + 15 = 315 seconds.
Example 2
Ahmed starts work at 9 a.m. and finishes at 4:30 p.m.
For how many minutes is he at work?
Answer
From 9 a.m. to 4 p.m. is 7 hours so Ahmed is at work for 7½ hours.
1 hour = 60 minutes.
½ hour = 30 minutes.
7½ hours = 7 × 60 + 30 = 420 + 30 = 450 minutes.