# 1997 - WAEC Mathematics Past Questions and Answers - page 1

1
Express (0.0425 / 2.5) as a fraction
A
17/10,000
B
17/1,000
C
17/250
D
17/100
correct option: b
0.0425/2.5 =
425/25000 =
17/1000
2

If P = {3, 5, 6} and Q = {4, 5, 6} then P∩Q equals

A
{3, 4}
B
{4, 5}
C
{4, 6}
D
{5, 6}
correct option: d

P ∩ Q = {5, 6}

3
A and B are two sets. The number of elements in A∪B is 49, the number in A is 22 and number in B is 34. How many elements are in A ∩ E?
A
105
B
27
C
15
D
12
correct option: e
Let x represent the intersection
34 - x + 22 - x + x = 49
- x = 49 - 56; x = 7
4

A student found the approximate value of 0.02548 correct to two places of decimal instead of two significant figures. Find the percentage error.

A
0%
B
131/3%
C
15 5/13%
D
2/3%
correct option: e

0.02548 $$\approxeq$$ 0.03 (to 2 decimal places)

0.02548 $$\approxeq$$ 0.025 (2 sig. figs)

Error = 0.03 - 0.025

= 0.005

% error = $$\frac{0.005}{0.025} \times 100%$$

= 20%

5
Simplify log39 + log315 - log35
A
log319
B
log3
C
3
D
1
correct option: c
log3
(9 x 15)/5 = log327 = 3
6
Solve me equation: 2/3 (x + 5) = 1/4(5x - 3)
A
11/7
B
18/23
C
3
D
43/7
correct option: e
2/3 (x + 5) = 1/4(5x - 3)
8x + 40 = 15x - 9
-7x = -49
x = 7
7

Which of the following equations has its roots as 4 and -5?

A
x2 + 4x - 20 = 0
B
x2 + x + 20 = 0
C
x2 - x + 20 = 0
D
x2 + x - 20 = 0
correct option: d

(x - 4)(x + 5) = 0
x$$^2$$ + 5x - 4x - 20 = 0
x$$^2$$ + x - 20 = 0

8

Solve the equations: 4x -y = 11; 5x + 2y = 4.

A
x = 6, y = 13
B
x = -2, y = -3
C
x = -2, y = 3
D
x = 2, y = -3
correct option: d

4x - y = 11....(1) x 2     8x - 2y = 22....(3)

5x + 12y = 4....(2) x 1     5x + 2y = 4....(4)

13x = 26

x = 2

4(2) - y = 11 $$\implies$$ y = 8 - 11

y = -3.

9
Make q the subject of the relation t = pq/r  - r2
A
q =
rt2/p - r3
B
q =
t2/p - r2
C
q =
rt/p - r3
D
q =
p - r3/rt2
correct option: a
t = pq/r - r2q
t2 =
pq - r3q/2
q(p - r3) = rt2
q =
rt2/p - r3
10
P varies inversely as the square of W. When W = 4, P = 9. Find the value of P when W = 9
A
729/16
B
6
C
4
D
16/9
correct option: d
P α 1/w2; P = K/W2
9 = K/42; 9 = K/16
K = 9 x 16 = 144
P = K/W2; when w = 9
P = 144/92 = 144/81 = 16/9