The coefficients of variation of two distributions are $60$ and $70$. The standard deviations are $21$ and $16$ respectively. Find their means.

The mean life of a sample of $60$ bulbs was $650$ hours and the standard deviation was $8$ hours. $A$ second sample of $80$ bulbs has a mean life of $660$ hours and standard deviation $7$ hours. Find the overall standard deviation.

If $x_1, x_2, \ldots, x_n$ are $n$ observations such that $\sum_{i=1}^n x_i^2 = 400$ and $\sum_{i=1}^n x_i = 80$,then the least value of $n$ is

The expenditure of a family for a certain month were as follows:
Food - Rs. $560$,Rent - Rs. $420$,Clothes - Rs. $180$,Education - Rs. $160$,Other items - Rs. $120$
$A$ pie graph representing this data would show the expenditure for clothes by a sector whose angle equals......$^o$

If $G_1$ and $G_2$ are the geometric means of two series of sizes $n_1$ and $n_2$ respectively,and $G$ is the geometric mean of their combined series,then what is $\log G$ equal to?

The mean of $5$ numbers is $18$. If one number is excluded,their mean becomes $16$. Then the excluded number is