Mean - Jamb Mathematics Past Questions and Answers

Question 21:

• JAMB 1986

If Musa scored 75 in biology instead of 57, his average mark in four subjects would have been 60. What was his total mark?

A. 282
B. 240
C. 222
D. 210

Question 22:

• JAMB 1989

In a family of 21 people, the average age is 14years. If the age of the grandfather is not counted, the average age drops to 12 years. What is the age of the grandfather?

A. 35 years
B. 40 years
C. 42 years
D. 54 years

Question 23:

• JAMB 1990

The mean of ten positive numbers is 16. When another number is added, the mean becomes 18. Find the eleventh number

A. 3
B. 16
C. 18
D. 38

Question 24:

• JAMB 1990

Below are the scores of a group of students in a test
\(\begin{array}{c|c} Scores & 1 & 2 & 3 & 4 & 5 & 6 \\ \hline \text{No. of students} & 1 & 4 & 5 & 6 & x & 2\end{array}\)
If the average scores is 3.5, find the value of x

A. 1
B. 2
C. 3
D. 4

Question 25:

• JAMB 1991

Fifty boxes each of 50 bolts were inspected for the number which were defective. The following was the result
\(\begin{array}{c|c} \text{No. defective per box} & 4 & 5 & 6 & 7 & 8 & 9 \\ \hline \text{No. of boxes} & 2 & 7 & 17 & 10 & 8 & 6\end{array}\)
The mean and the median of the distribution are respectively

A. 6.7, 6
B. 7.6, 5
C. 5.7, 87
D. 34, 6