Question
Mathematics Question on Mean Deviation
The mean of two samples of size 200 and 300 were found to be 25, 10 respectively. Their standard deviations were 3 and 4 respectively. The variance of combined sample of size 500 is
A
64
B
65.2
C
67.2
D
64.2.
Answer
67.2
Explanation
Solution
Answer (c) 67.2