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# S1 Maths Question. why.... watch

1. Find the number of students who took between 40 and 60 seconds.

The number of students who took between 60 and 70 seconds is 90.

The frequency between 40-60 is 100.
Frequency between 60-70 is 60

To find 1 unit 90/60 = 1.5

But why do i need to mutliply 100 by 1.5 to get the answer. Wouldn't the total umber of students just be 100.
Can someone explain why i need to mutiply it by 1.5 to get the actual total?????
2. (Original post by Elehin)
Find the number of students who took between 40 and 60 seconds.

The number of students who took between 60 and 70 seconds is 90.

The frequency between 40-60 is 100.
Frequency between 60-70 is 60

To find 1 unit 90/60 = 1.5

But why do i need to mutliply 100 by 1.5 to get the answer. Wouldn't the total umber of students just be 100.
Can someone explain why i need to mutiply it by 1.5 to get the actual total?????
90 students are represented by a frequency (density?) of 60.. which is why you've found 1 unit (the ratio).

So a frequency of 100 represents...
3. (Original post by SeanFM)
90 students are represented by a frequency (density?) of 60.. which is why you've found 1 unit (the ratio).

So a frequency of 100 represents...
I'm baffled i don't get why you multiply the 1.5 by 100.
Why can't the answer just be 100.
4. (Original post by Elehin)
I'm baffled i don't get why you multiply the 1.5 by 100.
Why can't the answer just be 100.
The same way you get from 90 to 60, but in the opposite direction.

Think of 1.5 as a scale factor - when you get a frequency of 60 it actually represents 90 people (60*1.5 = 90) which you've worked out from information in the question, so when you get a frequency of 100 that represents.. 100 * 1.5 people.
5. (Original post by SeanFM)
The same way you get from 90 to 60, but in the opposite direction.

Think of 1.5 as a scale factor - when you get a frequency of 60 it actually represents 90 people (60*1.5 = 90) which you've worked out from information in the question, so when you get a frequency of 100 that represents.. 100 * 1.5 people.
Oh it's like a scale factor which helps to get the actual total.

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Updated: November 7, 2015
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