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WAEC Mathematics Past Questions & Answers - Page 141

701.

Simplify: (3 $\frac{1}{2} + 4\frac{1}{3}) \div (\frac{5}{6} - \frac{2}{3}$ )

1 $\frac{1}{4}$

8 $\frac{1}{2}$

Correct answer is D

(3 $\frac{1}{2} + 4\frac{1}{3}) \div (\frac{5}{6} - \frac{2}{3}$ ) = (7 $\frac{3 + 2}{6}) \div \frac{(5 - 4)}{6}$

7 $\frac{5}{6} \div \frac{1}{6} = \frac{47}{6} \times \frac{6}{1}$ = 47

702.

Every staff in an office owns either a Mercedes and/or a Toyota car. 20 own Mercedes, 15 own Toyota and 5 own both. How many staff are there in the office?

View answer & explanation

Correct answer is B

M = Mercedez; T = Toyota

Number of staff = 0 + (20 - 5) + (15 - 5) + 5

0 + 15 + 10 + 5 = 30

703.

In the diagram, find the size of the angle marked a°

60^o

80^o

120^o

160^o

View answer & explanation

Correct answer is B

2 x s = 280°(Angle at centre = 2 x < at circum)

S = $\frac{280^o}{2}$

= 140°

< O = 360 - 280 = 80°

60 + 80 + 140 + a = 360°

(< in a quad); 280 + a = 360

a = 360 - 280

a = 80°

704.

In the diagram, < QPR = 60^o

< PQR = 50^o

< QRS = 2x^o

< SRP = 3x^o

< UQP = y^o and RS//TU

calculate y

102^o

78^o

70^o

60^o

View answer & explanation

Correct answer is A

< RQT = < QRS = 2x (Alternate angles). But in $\bigtriangleup$ PRQ

50 + 60 + (2x + 3x) = 180^o(Angles in a triangle)

110 + 5x = 180^o

5x = 180^o - 110 = 70^o

x = $\frac{70}{5}$ = 14^o

Also y + 50 + 2(14) = 180^o

y + 50 + 28 = 180^o

y = 180 - 78

y = 102^o

705.

In the diagram, PX is a tangent to the circle and RST is an equilateral triangle. Calculate < PTS

60^o

90^o

120^o

150^o

View answer & explanation

Correct answer is C

$\bigtriangleup$ RST is equilateral triangle, hence

< TRS = < RTS = < RSt = 60^o

But < PTR = 60^o(Angle between a chord and a tangent at the point of contact = Angle in the alt. segment). From the diagram < PTS = < PTR + < RTS

= 60^o + 60^o = 120^o