2017 - WAEC Mathematics Past Questions & 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)

 

 

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