Question

"Radon: The Problem No One Wants to Face" is the title of an article appearing in Consumer Reports. Radon is a gas emitted from the ground that can collect in houses and buildings. At certain levels it can cause lung cancer. Radon concentrations are measured in picocuries per liter (pCi/L). A radon level of 4 pCi/L is considered "acceptable." Radon levels in a house vary from week to week. In one house, a sample of 8 weeks had the following readings for radon level (in pCi/L).

1.9

2.2

5.7

5.2

1.9

8.3

3.9

7.1

(a) Find the mean, median, and mode. (Round your answers to two decimal places.)

mean
median
mode

(b) Find the sample standard deviation, coefficient of variation, and range. (Round your answers to two decimal places.)

s
CV	%
range

Answer 1

Computational Table:

	X	Xi-Mean	(Xi-mean)2
	1.9	-2.625	6.8906
	2.2	-2.325	5.4056
	5.7	1.175	1.3806
	5.2	0.675	0.4556
	1.9	-2.625	6.8906
	8.3	3.775	14.2506
	3.9	-0.625	0.3906
	7.1	2.575	6.6306
Total	36.2	0.00	42.2950

a)

Mean:

Median:

First Arrange the data in Ascending order:

1.9, 1.9, 2.2, 3.9, 5.2, 5.7, 7.1, 8.3

Median = For an even number of data values, the median is found by dividing the sum of the two middle values by two.

Median = (3.9 + 5.2) /2 = 9.1 / 2 = 4.55

Mode: The value or property that occurs most frequently in the data.

Here, 1.9 repeats maximum times, i.e. 2 times.

Therefore, Mode = 1.9

b)

Standard deviation = S =  

CV = Coefficient of variation = (S / Mean) * 100 = (2.46 / 4.53) * 100 = 54.32%

Range = Maximum value - Minimum Value = 8.3 - 1.9 = 6.4