WAEC Mathematics Past Questions & Answers - Page 199

991.

PQRS is a cyclic quadrilateral. If ∠QPS = 75°, what is the size of ∠QRS?

A.

180o

B.

150o

C.

105o

D.

75o

Correct answer is C

< QPS = 75°

< QRS = 180° - 75° = 105° (opposite angles of a cyclic quadrilateral)

992.

A pyramid of volume 120cm3 has a rectangular base which measures 5cm by 6cm. Calculate the height of the pyramid

A.

5cm

B.

9cm

C.

12cm

D.

15cm

Correct answer is C

\(V= \frac{1}{2}\hspace{1mm}base\hspace{1mm}area\hspace{1mm}\times\hspace{1mm}height\\
120=\frac{1}{3}\times 5 \times 6 \times h; h = \frac{120}{10}=12cm\)

993.

Evaluate \(\frac{log8}{log\left(\frac{1}{4}\right)}\)

A.

-2

B.

\(\frac{-3}{2}\)

C.

\(\frac{1}{2}\)

D.

4

Correct answer is B

\(\frac{log8}{log\frac{1}{4}}=\frac{log2^3}{log2^{-2}}=\frac{3log2}{-2log2}=-\frac{3}{2}\)

994.

Find the value of x which satisfies the equation
5(x-7)=7-2x

A.

x =2

B.

x=4

C.

x=6

D.

x = 14

Correct answer is C

5(x - 7) = 7 - 2x

5x - 35 = 7 - 2x

5x + 2x = 7 + 35

7x = 42

x = \(\frac{42}{7}\)

= 6

995.

Simplify \(\left(1\frac{2}{3}\right)^2 - \left(\frac{2}{3}\right)^2\)

A.

\(2\frac{1}{3}\)

B.

\(1\frac{1}{3}\)

C.

1

D.

\(\frac{3}{7}\)

Correct answer is A

\(\left(1\frac{2}{3}\right)^2 - \left(\frac{2}{3}\right)^2=\left(\frac{5}{3}\right)^2 - \left(\frac{2}{3}\right)^2\)
Difference of two squares
\(\left(\frac{5}{3}-\frac{2}{3}\right)\left(\frac{5}{3}+\frac{2}{3}\right)=\left(\frac{3}{3}\right)\left(\frac{7}{3}\right)\\
\frac{7}{3}=2\frac{1}{3}\)