The following table shows the ages of the patients admitted in a hospital during a year:

Age (in year)	5-15	15-25	25-35	35-45	45-55	55-65
Number of patients	6	11	19	23	14	7

Find the mean of the above data.

If the mean of $x-3$, $x+4$, $2x-1$, $x+3$ is 2. The value of x is :

The A.M.(Arithmetic Mean) and G.M (Geometric Mean) of two positive numbers p and q are 8 and 4 respectively, then the value of p - q are

Find the mean deviation about the median for the following data set:

3, 9, 5, 3, 12, 10, 18, 4, 7, 19, 21.

The median and mean of 7 observations are 9 and 11 respectively. If 2 is subtracted from each observation, then the new median and the new mean will respectively be which of the following?

The following are the marks obtained in a class test by a student: 10, 12, 15, 15, 18, 20, 20, 20, 23. The variance is?

If the mean of five observations x + 1, x + 2, x + 3, x + 4 and x + 5 is 15, then what is the mean of the first three observations?