# 2017 - WAEC Mathematics Past Questions and Answers - page 1

1

Express 0.0000407, correct to 2 significant figures

A
0.0
B
0.00004
C
0.000041
D
0.0000407
correct option: c

0.0000407 to 2 s.f

0.000041 (2 s.f)

2

If x varies inversely as y and y varies directly as z, what is the relationship between x and z?

A
x $$\alpha$$ z
B
x $$\alpha$$ $$\frac{1}{z}$$
C
a $$\alpha$$ z$$^2$$
D
x $$\alpha$$ $$\frac{1}{z^2}$$
correct option: b

$$x \propto \frac{1}{y}$$, y $$\propto$$ z

x = $$\frac{k}{y}$$

y = mz

Since y = mz,

x = $$\frac{k}{mz}$$, where k and m are constants. Hence,

x $$\propto$$ $$\frac{1}{z}$$

3

Evaluate $$\frac{3\frac{1}{4} \times 1\frac{3}{5}}{11\frac{1}{3} - 5 \frac{1}{3}}$$

A
$$\frac{14}{15}$$
B
$$\frac{13}{15}$$
C
$$\frac{4}{5}$$
D
$$\frac{11}{15}$$
correct option: b

$$\frac{3\frac{1}{4} \times 1\frac{3}{5}}{11\frac{1}{3} - 5 \frac{1}{3}}$$ = $$\frac{\frac{26}{5}}{\frac{18}{3}}$$ = $$\frac{26}{5} \div \frac{18}{3}$$

= $$\frac{13}{15}$$

4

The ages of Tunde and Ola are in the ratio 1:2. If the ratio of Ola's age to Musa's age is 4:5, what is the ratio of Tunde's age to Musa's age?

A
1 : 4
B
1 : 5
C
2 : 5
D
5 : 2
correct option: c

Tunde: Ola $$\to$$ 1 : 2 ; Ola; Musa $$\to$$ 4 : 5

$$\frac{1}{2}$$ x $$\frac{4}{5}$$

= $$\frac{2}{5}$$

5

If M = {x : 3 $$\leq$$  x < 8} and N = {x : 8 <  x $$\leq$$ 12}, which of the following is true?

i. 8 $$\in$$ M $$\cap$$ N

ii. 8 $$\in$$ M $$\cup$$ N

iii. M $$\cap$$ N = $$\varnothing$$

A
iii only
B
i and ii
C
ii and iii only
D
i, ii and iii
correct option: a

M = {3, 4, 5, 6, 7,}, N = {9, 10, 11, 12}

6

Given that a = log 7 and b = $$\log$$ 2, express log 35 in terms of a and b.

A
a + b + 1
B
ab - 1
C
a - b + 1
D
b - a + 1
correct option: c

$$\frac{\log 7 \times \log 10}{\log 2}$$

log 7 x log 10 $$\div$$ log 2

a + 1 - b

a - b + 1

7

If x = $$\frac{2}{3}$$ and y = - 6, evaluate xy - $$\frac{y}{x}$$

A
0
B
5
C
8
D
9
correct option: b

x = $$\frac{2}{3}$$ and y = - 6

xy - $$\frac{y}{x}$$

$$\frac{2}{3} - (6)^2 - (-6) \div \frac{2}{3}$$

= -4 - (6) x $$\frac{3}{2}$$

= -4 - (-6) x $$\frac{3}{2}$$

= -4 - (-9)

= -4 + 9

= 5

8

Solve the equation: $$\frac{1}{5x} + \frac{1}{x}$$= 3

A
$$\frac{1}{5}$$
B
$$\frac{2}{5}$$
C
$$\frac{3}{5}$$
D
$$\frac{4}{5}$$
correct option: b

$$\frac{1}{5x} + \frac{1}{x}$$= 3

$$\frac{1 + 5}{5x}$$ = 3

6 = 15x

x = $$\frac{6}{15}$$

= $$\frac{2}{5}$$

9

A sum of N18,100 was shared among 5 boys and 4 girls with each boy taking N20.00 more than each girl. Find a boy's share.

A
N1,820.00
B
2,000.00
C
N2,020.00
D
N2,040.00
correct option: c

Let a girl's share = x + 20

4x + 5(x + 20) = 18,100

4x + 5x + 100 = 18,100

9x + 100 = 18,100

9x = 18,000

x = $$\frac{18,000}{9}$$

x = 2,000

$$\therefore$$ Each boy gets N(2,000 + 20)

= N2,020.

10

One factor of $$7x^2 + 33x - 10$$ is

A
7x + 5
B
x - 2
C
7x - 2
D
x - 5
correct option: c

$$7x^2 + 33x - 10$$

$$7x^2 + 35x - 2x - 10$$

7x (x + 5) - 2 (x + 5)

(7x - 2) (x + 5)