Jamb Mathematics 1998 Past Questions and Answers

Question 31:

• JAMB 1998

If m and n are the mean and median respectively of the set of numbers 2, 3, 9, 7, 6, 7, 8, 5, find m + 2n to the nearest whole number

A. 19
B. 18
C. 13
D. 12

Question 32:

• JAMB 1998

\(\begin{array}{c|c} \text{Average hourly earnings(N)} & 5 - 9 & 10 - 14 & 15 - 19 & 20 - 24\\ \hline \text{No. of workers} & 17 & 32 & 25 & 24\end{array}\)
Estimate the mode of the above frequency distribution

A. 12.2
B. 12.27
C. 12.9
D. 13.4

Question 33:

• JAMB 1998

Find the variance of the numbers k, k+1, k+2,

A. \(\frac{2}{3}\)
B. 1
C. K + 1
D. (k + 1)²

Question 34:

• JAMB 1998

Find the positive value of x if the standard deviation of the numbers 1, x + 1 is 6

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

Question 35:

• JAMB 1998

A bag contains 16 red balls and 20 blue balls only. How many white balls must be added to the bag so that the probability of randomly picking a red ball is equal to \(\frac{2}{5}\)

A. 4
B. 20
C. 24
D. 40