Question

Sheet 3 Question (1) I- A random sample of 7 pieces of cotton fiber was taken and the absorbency values of each piece was given as follows: 18.71 21.81 20.14 21.81 17.29 22.56 20.17 From the data compute: a) two measures of central tendency. b) two measures of dispersion. Solution:

Answer 1

1:

Following table shows the ordered data set and calculations for mean and SD:

	X	(X-mean)^2
	17.29	9.4249
	18.71	2.7225
	20.14	0.0484
	20.17	0.0361
	21.81	2.1025
	21.81	2.1025
	22.56	4.84
Total	142.49	21.2769

Sample size n = 7 Sample sum: Ex=142.49 Sample mean: F-2 -142.49/7 n =20.36

Median: Theer are 7 data values so median will be 4th data value. So median is 20.17.

(b)

Sample standard deviation: - Esqrt(21.2769/(7-1)) V n-1 =1.8831