Video: AQA GCSE Mathematics Foundation Tier Pack 4 • Paper 3 • Question 3

How many seconds are there in 10 1/3 minutes? Circle your answer. [A] 120 [B] 130 [C] 620 [D] 630


Video Transcript

How many seconds are there in 10 and a third minutes? Circle your answer. The options are 120, 130, 620, and 630.

So to help us the solve this problem, we’re gonna use a conversion factor. And the conversion factor we know is that one minute is equal to 60 seconds. And what we want to know is how many seconds are in 10 and a third minutes. So first of all, we’re gonna try and work out how many seconds are in 10 minutes. Well, if we multiply one by 10, we get 10. So therefore, what we’re gonna do is multiply both sides by 10. So therefore, we get that 10 minutes is equal to 600 seconds. And we got that because if you multiply 60 by 10, you get 600. A simple way of doing it is adding a zero. However, what’s actually happening is that each digit is moving one place value to the left. So the six is going from being a 10 to 100.

Well, if we know that there are 600 seconds in 10 minutes, it means that we can rule out two of the answers straightaway. We can rule out the 120 and 130 straightaway because we’ve already got 600 seconds. And we haven’t had the third of a minute yet. So they’re ruled out. So we’re left with 620 or 630. So now, what we want to do is work out what a third of a minute is in seconds.

So to do that, we’re gonna divide each side by three starting from the one minute equals 60 seconds. And that’s because if you have one divided by three, it’s the same as a third. So therefore, we can say that a third of a minute is equal to 20 seconds. And that’s because 60 divided by three is 20. And we could have done that mentally because if we think about six divided by three. Well, this is two. And then, we’ve got a zero because it was 60 divided by three. So therefore, we can say that 10 and a third minutes is gonna be equal to 600 seconds plus 20 seconds. Well, if we add 620, we get 620 seconds.

So therefore, we can say that there are 620 seconds in 10 and a third minutes. And we’ve circled that as it’s the third answer. It is worth remembering though that a third of a minute is 20 seconds and a quarter of a minute is 15 seconds. And this works the same with hours. A third of an hour is 20 minutes and a quarter of an hour is 15 minutes cause this would be very useful for questions like this.

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