Thirty households in a Paarl suburb were surveyed to identify their average water usage per month (in kilolitres, kl). The usage per household was:
|
10
|
18
|
30
|
13
|
42
|
14
|
9
|
15
|
19
|
20
|
|
25
|
15
|
24
|
12
|
15
|
16
|
22
|
22
|
8
|
33
|
|
50
|
26
|
16
|
32
|
25
|
26
|
16
|
26
|
25
|
12
|
Use Excel's Data > Data Analysis > Descriptive Statistics option and, where necessary, the function keyQUARTILE to answer the following questions:
(a) Find the mean, median and modal water usage across the 30 households.
(b) Find the variance and standard deviation of water usage per household.
(c) Find the first and the third quartile of water usage amongst the 30 households.
(d) Interpret the findings from (a) to (c) for the municipal officer who conducted this survey.
(e) If there are 750 households in the Paarl suburb, what is the most likely total water usage (in kl) amongst all these households:
(i) in a month?
(ii) in a year?