Question

The two box-and-whisker plots below show the scores on a math exam for two classes. What do the interquartile ranges tell you about the two classes?

a)Overall class A performed better than class B
b)Class B has more consistent scores
c)Class A has more consistent scores
d)Overall class B performed better than class A

Answer 1

The interquartile range (IQR) is the set of values from Q1 to Q3
Q1 = first quartile = left edge of the box
Q3 = third quartile = right edge of the box
It turns out that,
IQR = Q3 - Q1

Also, the IQR spans the middle 50% of the data set. The smaller the IQR is, the more consistent the data values are. We see that class B has a smaller IQR. Why? Because of the smaller box compared to class A

Therefore, the answer is choice B) Class B has more consistent scores

There is less variability in class B