Question

A set of nine data points is shown below.

8, 11, 12, 10, 9, 7, 5, 3, 9
Which statement is true if a tenth data point of 45 is added to the data set?
А
The mean and median will both increase.
B
The mean will increase and the median will decrease.
с
The mean will increase and the median will remain the same.
D
The mean and median will both decrease.
SED

Answer 1

C.

Explanation:

Reorder the data set, from least to greatest.

3, 5, 7, 8, 9, 9, 10, 11, 12

Mean: 8.2 -> you get this by adding up all the numbers in the data set by how many numbers in the data set. For example, 3+5+7+8+9+9+10+11+12= 74 divide by 9 (the numbers in the data set) = 8.2 (repeated infinitely).

Median: 9 -> you get this by finding the number in the middle of the data set, which is why you have to reorder the data set for the beginning to make this easier.

Mean (with 45): 11.9 -> 119 when you add up all the numbers, then divide by 10 because that's have many numbers in the new data set.

Median (with 45): 9 -> When there are two numbers in the middle of the data set, add them up and divide by two. For example, 9+9=18/2= 9

Answer: C.