A grouped data set has the following frequency distribution
MATHEMATICS · Subjective · A Level · Mathematics · Data presentation and interpretation · Data presentation and interpretation
Problem
A grouped data set has the following frequency distribution.
Class midpoint (x): 10, 20, 30, 40
Frequency (f): 3, k, 5, 2
The mean of the distribution is 25 and the standard deviation (correct to one decimal place) is 10.4.
(i) Establish an equation in k using the condition on the mean.
(ii) Using the condition on the standard deviation, obtain a second equation in k.
(iii) Solve the two equations to find the value of k.