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WAEC Mathematics Past Questions & Answers - Page 108

536.

A side and a diagonal of a rhombus are 10cm and 12cm respectively, Find its area

20cm²

24cm²

48cm²

96cm²

View answer & explanation

Correct answer is D

No explanation has been provided for this answer.

537.

The volume of a cuboid is 54cm3. If the length, width and height of the cuboid are in the ratio 2:1:1 respectively, find its total surface area

108cm²

90cm²

80cm²

72cm²

View answer & explanation

Correct answer is B

V = L x B x H

V = $2x \times x \times x = 2x^3$

= 54cm3

i.e. 2x3 = 54

x3 = $\frac{54}{2}$ = 27

x = 3 $\sqrt{27}$

x = 3

L = 2x i.e. 2 x 3 = 6cm

B = x i.e. x = 3cm

H = x i.e. x = 3cm

but A = 2(LB + LH + BH) = 2(6 x 3) + (6 x 3) + (3 x 3) = 2(18 + 18 + 9) = 2(45)

= 90cm2

538.

Find the coefficient of m in the expression of ( $\frac{m}{2} - 1 \frac{1}{2}$ ) (m + $\frac{2}{3}$ )

- $\frac{1}{6}$

- $\frac{1}{2}$

-1

-1 $\frac{1}{6}$

View answer & explanation

Correct answer is D

( $\frac{m}{2} - 1\frac{1}{4}$ )(m + $\frac{2}{3}$ )

( $\frac{m}{2} - \frac{3}{2}$ )( $\frac{m}{1} + \frac{2}{3}$ )

= $\frac{m^2}{3} + \frac{3m}{6} - \frac{6}{6}$

= $\frac{2m - 9m}{6}$

= $\frac{-7m}{6}$

= 1 $\frac{1}{6}$

539.

The sum of the interior angles of regular polygon is 1800^o. How many sides has the polygon?

View answer & explanation

Correct answer is B

Sum = (n - 2)180

1800 = (n - 2)180

divide both sides by 180^o

$\frac{1800}{180}$ = (n - 2) $\frac{180}{180}$

10 = n - 2

10 + 2 = n

n = 12

540.

Solve ( $\frac{27}{125}$ )^{- $\frac{1}{3}$} x ( $\frac{4}{9}$ )^{$\frac{1}{2}$}

$\frac{10}{9}$

$\frac{9}{10}$

$\frac{2}{5}$

$\frac{12}{125}$

View answer & explanation

Correct answer is A

( $\frac{27}{125}$ )^{- $\frac{1}{3}$} x ( $\frac{4}{9}$ )^{$\frac{1}{2}$}

= ( $\frac{3^3}{5^3}$ )^{- $\frac{1}{3}$}_{- $\frac{1}{3}$} x ( $\frac{3^2}{3^2}$ )^{$\frac{1}{2}$} _{- $\frac{1}{2}$}

= $\frac{3^{-1}}{3^{-1}} \times \frac{2}{3}$

= $\frac{\frac{1}{3}}{\frac{1}{5}} \times \frac{2}{3}$

$\frac{1}{3} \times \frac{5}{1} \times {2}{3} = \frac{10}{9}$