WAEC Mathematics Past Questions & Answers - Page 198

986.

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

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

987.

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

988.

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
\(\left(\frac{5}{3}-\frac{2}{3}\right)\left(\frac{5}{3}+\frac{2}{3}\right)=\left(\frac{3}{3}\right)\left(\frac{7}{3}\right)\\
\frac{7}{3}=2\frac{1}{3}\)

989.

Three men, Bedu, Bakre and Kofi shared' N500 in the ratio 3:2: x respectively. If Bedu’s share is N150, find the value of x.

A.

1

B.

4

C.

5

D.

6

Correct answer is C

\(5+x\rightarrow 500\\
3 \rightarrow 150\\
∴ 3 \times 500 = 150 \times (5+x)\\
1500 = 750 + 150x\\
x=\frac{750}{150}=5\)

990.

In the diagram, PQ/RT /RS/ =/QS/, ∠QST= 70° and ∠PQW = 55°
Find the size of reflex ∠WQS

A.

235o

B.

290o

C.

305o

D.

325o

Correct answer is A

Reflex ∠WQS = 360° - (55° + 70°)
=360° - 125° = 235°