# 1990 - WAEC Mathematics Past Questions and Answers - page 1

1

Simplify 125$$^{\frac{-1}{3}}$$ x 49$$^{\frac{-1}{2}}$$ x 10$$^0$$

A
350
B
35
C
1/35
D
1/350
correct option: c

125$$^{\frac{-1}{3}}$$ x 49$$^{\frac{-1}{2}}$$ x 10$$^0$$

= 5$$^{-1}$$ x 7$$^{-1}$$ x 1

= $$\frac{1}{35}$$

2

If 3$$^{2x}$$ = 27, what is x?

A
1
B
1.5
C
4.5
D
18
correct option: b

3$$^{2x}$$ = 27

3$$^{2x}$$ = 3$$^3$$

2x = 3

x = 1.5

3

Express 0.00562 in standard form

A
5.62 x 10-3
B
5.62 x 10-2
C
562 x 10-2
D
5.62 x 102
correct option: a

0.00562 = 5.62 x 10$$^{-3}$$

4
Given that 1/3log10 P = 1, find the value of P
A
1/10
B
3
C
10
D
100
correct option: e
1/3log10P = 1
log10P1/3 = log1010
P1/3 = 10 P = 1000
5

Simplify $$\frac{\log \sqrt{8}}{\log 8}$$

A
1/3
B
1/2
C
1/3log√2
D
1/3log√8
correct option: b

$$\frac{\log \sqrt{8}}{\log 8}$$

= $$\frac{\log 8^{\frac{1}{2}}}{log 8}$$

= $$\frac{\frac{1}{2} \log 8}{\log 8}$$

= $$\frac{1}{2}$$

6
Evaluate using the logarithm table, log(0.65)2
A
1.6258
B
0.6272
C
0.6258
D
3.6258
correct option: d
log(0.65)2 = 2log(0.65) but log0.65 = 1.8129
∴2 x 1.8129 = 3.6258
7

If log x = $$\bar{2}.3675$$ and log y = 0.9750, what is the value of x + y? Correct to three significant figures

A
1.18
B
1.31
C
9.03
D
9.44
correct option: e

log x = $$\bar{2}.3675$$ ; log y = 0.9750

$$x = 10^{\bar{2}.3675} = 0.02331$$

$$y = 10^{0.9750} = 9.441$$

$$x + y = 9.4641 \approxeq 9.46$$

8

While doing his physics practical, Idowu recorded a reading as 1.12cm instead of 1.21cm. Calculate his percentage error

A
1.17%
B
6.38%
C
7.44%
D
8.035%
correct option: c

%error = $$\frac{1.21 - 1.12}{1.21} \times 100%$$

= $$\frac{9}{121} \times 100%$$

= 7.44%

9

Find the 4th term of an A.P, whose first term is 2 and the common difference is 0.5

A
0.5
B
2.5
C
3.5
D
4
correct option: c

$$U_{n} = a + (n - 1)d$$

$$U_{4} = 2 + (4 - 1) \times 0.5$$

= $$2 + 1.5$$

= 3.5

10
From the graph determine the roots of the equation y = 2x2 + x - 6
A
-3, 4
B
-2, -6
C
-2, 1.5
D
-1, 1
correct option: c