Question

Which category contains Q3?

Answer 1

First step:
Find number of data points. How many?

Answer 2

14

Answer 3

Which is the independent variable?

Answer 4

idk how to find it

Answer 5

In a table like this, are we interested in the amount donated, or the number of donors?

Answer 6

amount donated?

Answer 7

Exactly!
What does the second line represent?

Answer 8

number of donors

Answer 9

yes, i.e. frequency.
Single variable distributions often come with frequency, as in the last problem.
What do we do next?

Answer 10

idk

Answer 11

As in the last problem, find the total number of data points. Can you do that?

Answer 12

Even better, can you find the cumulative frequencies?

Answer 13

229

Answer 14

The number of data points is the sum of the frequencies.
The table says that there are
10 people donated $5,
14 people donated $10,
8 people donated $15
....
So the number of data points is the number of people who donated.
can you find that?

Answer 15

89

Answer 16

Good. What is the rank of the middle data point.
(rank is the number of data points from the start).

Answer 17

This middle data point will be the median.

Answer 18

12

Answer 19

median of donors

Answer 20

The 12th data point would have 11 data points to the left, and 89-12=77 data points to the right, since 11 does not equal 77, 12th data point is not the median (middle data point).
Can you try again?

Answer 21

we want to find the median of donors?

Answer 22

5 8 10 12 13 14 27

Answer 23

middle is median ?

Answer 24

To find the median of donors, we need the rank of the middle donor out of 89.
Can you find the rank of the middle donor?

Answer 25

no

Answer 26

The middle (median) donor has the same number of data points to the left as to the right. It is around half of the data set.
For 89 data points (odd number), the middle donor is (89+1)/2=45th.
Note that the 45th data point has 44 to its left, and 44 to its right. ok?

Answer 27

ok

Answer 28

But we need Q3, which is the third quartile.

Answer 29

would it be 25?

Answer 30

The third quartile is the middle data point of the 44 data points to the right of the median.

So can you find the rank of Q3?
It is located between two data points, i.e. between the two groups of 22 data points.