Answer:
lower quartile: 80.5 upper quartile: 93
Explanation:
Fro the above question, we are given the following values for the number of cars 8 dealerships sold.
GMC = 84
Chevrolet = 81
Nissan = 92
Toyota = 92
Ford = 95
Honda = 94
Hyundai = 80
Acura = 72
We are told to find the lower and upper quartile of this set of data.
The lower quartile of a data set can be defined as the median( middle number) of the lower half of the data set. The lower quartile is also known or referred to as (Q1).
The lower quartile is also calculated using the formula
Q1 = 1/4(n + 1) th value
Where n is the number of values in the the date set.
The upper quartile of a data set can be defined as the median( middle number) of the upper half of the data set. The lower quartile is also known or referred to as (Q3).
The upper quartile is also calculated using the formula
Q3 = 3/4(n + 1) th value
Where n is the number of values in the the date set.
Step 1
Arrange the data set from the lowest to the highest number
72, 80, 81, 84, 92, 92, 94, 95
Step 2
Calculate the lower Quartile
Q1 = 1/4(n + 1)th value
n = number of values in the data set = 8 values
Q1 = 1/4(8 + 1)th value
Q1 = 1/4(9)th value
Q1 = 2.25th value
This means it is between the 2nd and 3rd value
2nd value = 80
3rd value = 81
(80 + 81) ÷ 2 = 161 ÷ 2 = 80.5
The Lower Quartile (Q1) = 80.5
Step 3
Calculate the lower Quartile
Q3 = 3/4(n + 1)th value
n = number of values in the data set = 8 values
Q3 = 3/4(8 + 1)th value
Q3 = 3/4(9)th value
Q3 = (27/4)th value
Q3 = 6.75th value
This means it is between the 6th and 7th value
6th value = 92
7th value = 94
(92 + 94) ÷ 2 = 186 ÷ 2 = 93
The Upper Quartile (Q3) = 93
Therefore, the Lower Quartile: 80.5 and Upper Quartile: 93