Question

Martin earned the following scores on his last five tests.

98, 78, 84, 75, 91

What is the interquartile range of his scores?


23
13
16
18
Can someone tell me how to do this? Thnx!

Answer 1

You know how to do ranges, yes?

Answer 2

98-75=x

Answer 3

yup, i can do ranges,

Answer 4

Then you can solve this question, no?

Answer 5

no, what is an interquartile?

Answer 6

It just means the range the answer is 23

Answer 7

The answer is not 23.

Answer 8

really hmmm wow my math is getting hiddeous

Answer 9

:(

Answer 10

The interquartile range is the difference between the upper and lower quartiles of a set of numbers. As an example the numbers
3 4 4 4 6 6 6 6 7 7 8 9
have upper quartile 7, lower quartile 4; so the interquartile range is 7 - 4 = 3

Answer 11

I thought that was just range?

Answer 12

when i do it that way, i get 23, and 23 is wrong.

Answer 13

A quartile is the value of a variable below which one quarter (lower quartile) or three quarters (upper quartile) of a distribution lie. the median is the second quartile.
Ordering the data in your question we get
75 78 84 91 98
Do you know which value is the median?

Answer 14

@lillybeth123 Do you know how to find the median?

Answer 15

yup i think it is 84.

Answer 16

Good! You are correct. So if the median is not included we get two subsets
{75, 78} and {91, 98}
The quartiles are the medians of these two subsets which in this case need to be the arithmetic means of the two numbers.
lower quartile = (75 + 78)/2 = ?
upper quartile = (91 + 98)/2 = ?
Can you calculate these two values?

Answer 17

yup, 76.5 and 94.4

Answer 18

Nearly right! The upper quartile is 94.5.
Now to find the interquartile range of the scores just subtract the lower quartile from the upper quartile;
94.5 - 76.5 = ?

Answer 19

oh, ok, 94.5, one minute for ur other problem.

Answer 20

18.

Answer 21

Good work! The correct answer choice is 18.

Answer 22

ok, so i just do the same thing for my problem?

Answer 23

Yes, 18 is the correct answer for the problem that you posted.

Answer 24

Thanks!!!!! :))))

Answer 25

You're welcome :)

Answer 26

Bye! :)