Mean - Jamb Mathematics Past Questions and Answers

Question 16:

• JAMB 1982

Determine the mean monthly salary of 50 employees of a company from the following frequency distribution.
\(\begin{array}{c|c} \text{Monthly salary} & \text{Frequency}\\\hline N200.00 & 10\\ N325.00 & 5\\N100.00 & 20\\N120.00 & 2\\ N60.00 & 10\\ N80.00 & 3\end{array}\)

A. N215.30
B. N134.10
C. N143.10
D. N80.00
E. N50.30

Question 17:

• JAMB 1982

The arithmetic mean of the ages of 30 pupils in a class is 15.3 years. One boy leaves the class and one girl is enrolled, and the new average age of 30 pupils in the class becomes 15.2 years. How much older is the boy than the girl?

A. 30 years
B. 6 years
C. 9 years
D. 3 years
E. 1 year

Question 18:

• JAMB 1983

Find the mean of the following 24.57, 25.63, 24.32, 26.01, 25.77

A. 25.12
B. 25.30
C. 25.26
D. 25.50
E. 25.75

Question 19:

• JAMB 1984

Thirty boys and x girls sat for a rest. The mean of the boys scores and that of the girls were respectively 6 and 8. Find x if the total scores was 468

A. 38
B. 24
C. 36
D. 22
E. 41

Question 20:

• JAMB 1984

Measurements of the diameters, in centimeters, in centimeters, of 20 copper spheres are distributed as shown below
\(\begin{array}{c|c} \text{Class boundary in cm} & \text{frequency} & \\\hline 3.35 - 3.45 & 3\\ 3.45 - 3.55 & 6\\ 3.55 - 3.65 & 7\\ 3.65 - 3.75 & 4\end{array}\)
What is the mean diameter of the copper spheres?

A. 3.40cm
B. 3.58cm
C. 3.56cm
D. 3.62cm