Jamb Mathematics 1981 Past Questions and Answers

Question 11:

• JAMB 1981

What is the area between two concentric circles of diameters 26cm and 20cm?

A. 100\(\pi\)
B. 169\(\pi\)
C. 69\(\pi\)
D. 9\(\pi\)
E. 269\(\pi\)

Question 12:

• JAMB 1981

Marks scored by some children in an arithmetic test are:5, 3, 6, 9, 4, 7, 8, 6, 2, 7, 8, 4, 5, 2, 1, 0, 6, 9, 0, 8.
The arithmetic mean of the marks is

A. 6
B. 5
C. 8
D. 7
E. 10

Question 13:

• JAMB 1981

The weights of 30 new-born babies are given as follow: 6, 9, 5, 7, 6, 7, 5, 8, 9, 5, 7, 5, 8, 7, 8, 7, 5, 6, 5, 7, 6, 9, 9, 7, 8, 8, 7, 8, 9, 8. The mode is

A. 6
B. 5
C. 8
D. 7
E. 10

Question 14:

• JAMB 1981

If \(\sin x° = \frac{a}{b}\), what is \(\sin (90 - x)°\)?

A. \(\frac{\sqrt{b^2 - a^2}}{b}\)
B. 1\(\frac{-a}{b}\)
C. \(\frac{b^2 - a^2}{b}\)
D. \(\frac{a^2 - b^2}{b}\)
E. \(\sqrt{b^2 - a^3}\)

Question 15:

• JAMB 1981

7 pupils of average age 12 years leave a class of 25 pupils of average age 14 years. If 6 new pupils of average age 11years join the class, what is the average age of the pupils now in the class?

A. 13years
B. 12 years 7\(\frac{1}{2}\) months
C. 13 years 5 months
D. 13 years 10 months
E. 11 years