The mean and variance of 8 observations are 10 and 13.5 respectively. If 6 of these observations are 5, 7, 10, 12, 14, 15, then the absolute difference of the remaining two observations is :
9
5
3
7
If the variance of the following frequency distribution :
Class : 10-20 20-30 30-40
Frequency : 2 x 2
is 50, then x is equal to ....
If the mean and the standard deviation of the data 3, 5, 7, a, b are 5 and 2 respectively, then a and b are the roots of the equation :
x2 - 20x + 18 = 0
2x2 - 20x + 19 = 0
x2 - 10x + 19 = 0
x2 - 10x + 18 = 0