(English Medium) ICSE Class 9 - CISCE Question Bank Solutions

The mean of 15 observations is 32. Find the resulting mean, if the observation is: Decreased by 7

The mean of 15 observations is 32. Find the resulting mean, if each observation is:  Multiplied by 2

The mean of 15 observations is 32. Find the resulting mean, if the observation is:  Divided by 0.5

The mean of 15 observations is 32. Find the resulting mean, if the observation is: Increased by 60%

Find the mean of 8, 12, 16, 22, 10 and 4. Find the resulting mean, if the observations, given above, be: multiplied by 3.

The mean of 15 observations is 32. Find the resulting mean, if the observation is: Decreased by 20%

Find the mean of 8, 12, 16, 22, 10 and 4. Find the resulting mean, if the observations, given above, be: multiplied by 3 and then divided by 2.

Find the median of: 25, 16, 26, 16, 32, 31, 19, 28 and 35

Find the mean of 8, 12, 16, 22, 10 and 4. Find the resulting mean, if each of the observations, given above, be:  increased by 25%

Find the mean of 8, 12, 16, 22, 10 and 4. Find the resulting mean, if each of the observations, given above, be:  decreased by 40%

The mean of 18, 24, 15, 2x + 1 and 12 is 21. Find the value of x. 

The heights (in cm) of the volleyball players from team A and team B were recorded as:
Team A: 180, 178, 176, 181, 190, 175, 187

Team B: 174, 175, 190, 179, 178, 185, 177

Which team had a greater average height?

Find the median of team A and team B.

The average of n numbers x₁, x₂, x₃ ….. x_n is A. If x₁ is replaced by  ( x+ α )x₁, x₂, is replaced by ( x+ α )x₂ and so on.
Find the new average.

The mean of 6 numbers is 42. If one number is excluded, the mean of the remaining number is 45. Find the excluded number.

The mean weight of 60 students in a class is 40 kg. The mean weight of boys is 50 kg while that of girls is 30 kg. Find the number of boys and girls in the class.

The mean of 10 numbers is 24. If one number is included, the new mean is 25. Find the included number. 

Find the mean and median of all the positive factors of 72.

The mean of x, x + 2, x + 4, x + 6 and x + 8 is 11, find the mean of the first three observations.

Find the mean and median of the data: 35, 48, 92, 76, 64, 52, 51, 63 and 71.
If 51 is replaced by 66, what will be the new median?

Find the mean of the following data: 30, 32, 24, 34, 26, 28, 30, 35, 33, 25
(i) Show that the sum of the deviations of all the given observations from the mean is zero.
(ii) Find the median of the given data.