# 1995 - WAEC Mathematics Past Questions & Answers - page 1

1

Find (101$$_2$$)$$^2$$, expressing the answer in base 2.

A
10101
B
11001
C
10010
D
11101
CORRECT OPTION: b

You can convert it to base 10 and square, then re-convert it after the operation.

OR

You can multiply it straight applying the rules of binary multiplication.

2
If three children shares N10.50 among themselves in ratio 6:7:8, how much is the largest share?
A
N3.00
B
N3.50
C
N4.00
D
N4.50
CORRECT OPTION: c
Ratio = 6 + 7 + 8 = 21
21 = N10.50
1 = 1050K/21 = 50K
6 = 6 x 50K = N3.00
7 = 7 x 50K = N3.50
8 = 8 x 50K = N4.00
the Largest share = N4.00
3
Express 0.000834 in standard form
A
8.34 x 10-4
B
8.34 x 10-3
C
8.34 x 103
D
8.34 x 104
CORRECT OPTION: a
4
Given that log2a = log84, find a
A
21/3
B
42/3
C
42/3
D
22/3
CORRECT OPTION: d
Log2a = Log84
Log2a = Log882/3 → 2/3Log88 → 2/3 x 1
Log2a = 2/3
Recall; If Logax = y ∴ ay = x
Log2a = 2/3
22/3 = a
5

By selling some crates of soft drinks for N600.00, a dealer makes a profit of 50%. How much did the dealer pay for the drinks?

A
N1,200.00
B
N900.00
C
N450.00
D
N400.00
CORRECT OPTION: d

S.P = N600.00

(100 + 50)% = N600

150% = N600

1% = $$\frac{600}{150}$$

100% = $$\frac{600}{150} \times 100%$$

= N400

6
Find the nth term Un of the A.P., 11, 4, -3,....... .
A
Un=19+7n
B
Un=19-7n
C
Un=18+7n
D
Un= 18-7n
CORRECT OPTION: d
A.P 11, 4, -3
1st term = 11
A.P = a, a + d, a + 2d ...... a + (n - 1)d
If a = 11
a + d = 4
d = 4 - 11 = -7
nth term = a + (n-1)d
= 11 + (n-1)(-7)
= 11 - 7n + 7
= 18 - 7n
7
lf 16/9 , x, 1, y are in Geometric Progression (GP), find the product of x and y.
A
9/16
B
3/4
C
1
D
4/3
CORRECT OPTION: c
16/9, x, 1, y => a, ar, ar2, ar3
ar2 = 1 => 16r2/9 = 1 => 16r2
9 => r2 = 9/16 => r = 3/4
ar2 = y = ar2 x r = 1 x 3/4 = 3/4
x xy = 4/3 x 3/4 = 1
8

If R = [2, 4, 6, 7] and S = [1, 2, 4, 8], then R∪S equal

A
[1,2,4,6,7,8]
B
[1,2,4,7,8]
C
[1,4.7,8]
D
[2.6.7]
CORRECT OPTION: a

R = {2, 4, 6, 7}; S = {1, 2, 4, 8}

R $$\cup$$ S = {1, 2, 4, 6, 7, 8}

9

Find the value(s) of x for which the expression is undefined: $$\frac{6x - 1}{x^2 + 4x - 5}$$

A
+4 or+1
B
-5 or +1
C
-5 or -1
D
+5 or -1
CORRECT OPTION: b

$$\frac{6x - 1}{x^2 + 4x - 5}$$

The expression is undefined when $$x^2 + 4x - 5 = 0$$

$$x^2 + 5x - x - 5 = 0$$

$$x(x + 5) - 1(x + 5) = 0$$

$$(x - 1)(x + 5) = 0$$

The expression is undefined when x = 1 or -5.

10

Which of the following could be the inequality illustrated in the sketch graph above?

A
y≥2x+3
B
y≤-3x+3
C
y < 3x+2
D
y≤x +3
CORRECT OPTION: b

Gradient of the line = $$\frac{3 - 0}{0 - 1}$$

= -3

y = -3x + b.

Using (1,0), we have

0 = -3(1) + b

0 = -3 + b

b = 3

y = -3x + 3

$$\therefore$$ The graph illustrates y $$\leq$$ -3x + 3.

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