# 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

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}

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

Users' Answers & Comments34 - 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 log

_{3}9 + log_{3}15 - log_{3}5A

log

_{3}19B

log

_{3}C

3

D

1

6

Solve me equation: 2/3 (x + 5) = 1/4(5x - 3)

A

1

^{1}/_{7}B

1

^{8}/_{23}C

3

D

4

^{3}/_{7}**correct option:**e

2/3 (x + 5) = 1/4(5x - 3)

8x + 40 = 15x - 9

-7x = -49

x = 7

Users' Answers & Comments8x + 40 = 15x - 9

-7x = -49

x = 7

7

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

A

x

^{2}+ 4x - 20 = 0B

x

^{2}+ x + 20 = 0C

x

^{2}- x + 20 = 0D

x

^{2}+ 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)

add eqn (3) and (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}- r^{2}A

q =

rt

^{2}/p - r^{3}B

q =

t

^{2}/p - r^{2}C

q =

rt/p - r

^{3}D

q =

p - r

^{3}/rt^{2}**correct option:**a

t = √

^{pq}/_{r}- r^{2}qt

^{2}=pq - r

q(p - r

^{3}q/2q(p - r

^{3}) = rt^{2}q =

rt

^{2}/p - r^{3}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/w

9 = K/4

K = 9 x 16 = 144

P = K/W

P = 144/9

Users' Answers & Comments^{2}; P = K/W^{2}9 = K/4

^{2}; 9 = K/16K = 9 x 16 = 144

P = K/W

^{2}; when w = 9P = 144/9

^{2}= 144/81 = 16/9