JAMB Mathematics Past Questions & Answers

951.

If x is jointly proportional to the cube of y and the fourth power of z. In what ratio is x increased or decreased when y is halved and z is doubled?

4:1 increase

2:1 increase

1:1 no change

1:4 decrease

3:4 decrease

View answer & explanation

Correct answer is B

$x \propto y^{3} z^{4}$

$x = ky^{3} z^{4}$

If y is halved and z is doubled, we have

$x = k (\frac{1}{2} y)^{3} (2z)^{4}$

$x = k (\frac{y^{3}}{8}) (16z^{4})$ \)

$x = 2k y^{3} z^{4}$

$\therefore \text{x is increased in the ratio 2 : 1}$

952.

Given a regular hexagon, calculate each interior angle of the hexagon

60^o

30^o

120^o

45^o

135^o

View answer & explanation

Correct answer is C

Sum of interior angles of polygon = (2n - 4)rt < s

sum of interior angles of an hexagon

(2 x 6 - 4) x 90^o = (12 - 4) x 90^o

= 8 x 90^o

= 720^o

each interior angle will have $\frac{720^o}{6}$

= 120^o

953.

A construction company is owned by two partners X and Y and it is agreed that their profit will be divided in the ratio 4:5. At the end of the year, Y received N5,000 more than X. What is the total profit of the company for the year?

N20, 000

N25,000

N30,000

N15,000

N45, 000

View answer & explanation

Correct answer is E

Total sharing ratio is 9 X has 4, Y has 4 + 1 If 1 is N5000 Total profit = 5000 x 9 = N45,000

954.

If M represents the median and D the mode of the measurements 5, 9, 3, 5, 7, 5, 8 then (M, D) is

(6, 5)

(5, 8)

(5, 7)

(5, 5)

(7, 5)

View answer & explanation

Correct answer is D

first re-arrange the given data in the form 3, 5, 5, 7, 8, 9 Mean(x) = $\frac{\sum x}{N}$

= $\frac{42}{7}$

= 6, re-arrange thenumbers,

3, 5, 5| 7, 8, 9 median(D) = 5

(m, d) = (5, 5)

955.

Measurements of the diameters, 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?

3.40cm

3.58cm

3.56cm

3.62cm

View answer & explanation

Correct answer is C

$\begin{array}{c|c} \text{x(mid point)} & f & fx\\ \hline 3.4 & 3 & 10.2 \\ 3.5 & 6 & 21.0\\3.6 & 7 & 25.2\\3.7 & 4 & 14.8\end{array}$

$\sum f$ = 20

$\sum fx$ = 71.2

mean = $\frac{\sum fx}{\sum f}$

= $\frac{71.2}{20}$

= 3.56