A set of eight observations is: 12, 15, 18, 20, 22, 24, 27 and x
MATHEMATICS · Multi-part · A Level · Mathematics · Data presentation and interpretation · Data presentation and interpretation
Problem
A set of eight observations is: 12, 15, 18, 20, 22, 24, 27 and x.
The arithmetic mean of the complete data is known to be 20.
(i) Find the value of the missing observation x.
(ii) Using the value of x obtained in part (i), calculate the variance of the complete data set.
(iii) Comment on whether the data are more or less dispersed than the numbers 10, 15, 20, 25, 30, 35, 40 and 45 whose variance is 125.