3.1 Converting units of time
You can see from the diagram below that to convert units of time you can use a very similar method to the one you used when converting other units of measure. There is one slight difference when working with time however.
N.B. Only one month has 4 weeks (February). The rest have between 30 and 31 days. On average there are 4.3 weeks in a month.>
Let’s say you want to work out how long 245 minutes is in hours. The diagram above shows that you should do 245 ÷ 60 = 4.083. This is not a particularly helpful answer since you really want the answer in the format of: ___ hours __ minutes. Due to the fact that time does not work in 10s, you need to do a little more work once arriving at your answer of 4.083.
The answer is obviously 4 hours and an amount of minutes.
4 hours then is 4 × 60 = 240 minutes.
Since you wanted to know how long 245 minutes is you just do 245 – 240 = 5 minutes left over. So 245 minutes is 4 hours and 5 minutes.
It’s a very similar process if you want to go from say minutes to seconds. Let’s take it you want to know how long 5 minutes and 17 seconds is in seconds. 5 minutes would be 5 × 60 = 300 seconds. You then have a further 17 seconds to add on so you do 300 + 17 = 317 seconds.
Have a go at the activity below to make sure you feel confident with converting times.
Activity 7: Converting times
Convert the following times:
- 6 hours and 35 minutes = ___ minutes.
- 85 minutes = ____ hours and ____ minutes.
- 153 seconds = ____ minutes and ___ seconds.
- 46 days = ___ weeks and ____days.
- 3 minutes and 40 seconds = ____ seconds.
Answer
6 hours = 6 × 60 = 360 minutes
360 minutes + 35 minutes = 395 minutes
85 minutes ÷ 60 = 1.417 (rounded to three d.p)
1 hour = 60 minutes.
85 minutes − 60 minutes = 25 minutes remaining
So 85 minutes = 1 hour and 25 minutes
153 seconds ÷ 60 = 2.55
2 minutes = 2 × 60 = 120 seconds
153 seconds − 120 seconds = 33 seconds remaining
So 153 seconds = 2 minutes and 33 seconds
46 days ÷ 7 = 6.571 (rounded to three d.p)
6 weeks = 6 × 7 = 42 days
46 days − 42 days = 4 days remaining
So 46 days = 6 weeks and 4 days
3 minutes = 3 × 60 = 180 seconds
180 seconds + 40 seconds = 220 seconds
Hopefully you found that activity fairly straightforward and are now feeling ready to move on to the next part of the ‘Units of measure’ session – Average speed.