Statistics — Practice

Question 1

Find the mean of 25, 30, 35, 40, 45.

Accepted Answer

Sum = 175. n = 5. Mean = 35.

Question 2

Find the median of 11, 7, 14, 8, 21, 5, 17.

Accepted Answer

Sorted: 5, 7, 8, 11, 14, 17, 21. n = 7 (odd). Median = ((7+1)/2)-th = 4th observation = 11.

Question 3

Find the mode of 2, 3, 3, 4, 5, 3, 6, 7.

Accepted Answer

3 occurs three times; everything else occurs once. Mode = 3.

Question 4

The mean of 5 numbers is 18. If one number is added and the new mean is 20, find the added number.

Accepted Answer

Original sum = 5 × 18 = 90. New sum = 6 × 20 = 120. Added number = 120 − 90 = 30.

Question 5

20 students scored: 7, 8, 9, 7, 6, 8, 9, 5, 7, 8, 9, 7, 6, 5, 8, 9, 7, 7, 6, 8. Build a frequency table and find the mode.

Accepted Answer

Frequencies — 5: 2, 6: 3, 7: 6, 8: 5, 9: 4. Mode = 7 (highest frequency 6).

Practice — Statistics