# 2010 - WAEC Mathematics Past Questions and Answers - page 1

1
A
6.03 x 109
B
6.02 x 109
C
6.03 x 10-9
D
6.02 x 10-9
correct option: d
0.000215215 x 0.000028

= 215 x 10-4 x 28 x 10-4

= 215 x 28 x 10-6-6

= 6020 x 10-12

= 6.020 x 103 x 10-12

= 6.02 x 103 - 12

= 6.02 x 10-9
2
Factorize: x + y - ax = ay
A
(x - y)(1 - a)
B
(x + y)(1 + a)
C
(x + y)(1 - a)
D
(x - y)(1 + a)
correct option: c
x + y - ax = ay

= (x + y) -a(x + y) = (x + y)(1 - a)
3
A car uses one litre of petrol for every 14km. If one of petrol cost N63.00, how far can the car go with N900.00 worth of petrol?
A
420km
B
405km
C
210km
D
200km
correct option: d
1 litre = N63.00

xlitres = N900.00

x x N63 = N900 x 1 litre

x = $$\frac{900}{63} \times litre$$

x = $$\frac{100}{7}$$ litres

Also, 1 litre = 14km

$$\frac{100}{7}$$ = y

y x 1 litre = $$\frac{100litre}{7}$$ x 14km

y = 20km
4
Correct 0.002473 to 3 significant figure
A
0.002
B
0.0024
C
0.00247
D
0.0025
correct option: c
5
Simplify 1$$\frac{1}{2} + 2\frac{1}{3} \times \frac{3}{4} - \frac{1}{2}$$
A
-2$$\frac{1}{3}$$
B
-2$$\frac{1}{4}$$
C
2$$\frac{1}{8}$$
D
2$$\frac{3}{4}$$
correct option: d
1$$\frac{1}{2} + 2\frac{1}{3} \times \frac{3}{4} - \frac{1}{2}$$

$$\frac{3}{2} + \frac{7}{3} \times \frac{3}{4} - \frac{1}{2} = \frac{3}{2} + \frac{7}{4} - \frac{1}{2}$$

= $$\frac{6 + 7 - 2}{4} = \frac{11}{4}$$

= 2$$\frac{3}{4}$$
6
The sum of 2 consecutive whole numbers is $$\frac{5}{6}$$ of their product, find the numbers
A
3, 4
B
1, 2
C
2, 3
D
0, 1
correct option: c
Let the no. be x and x + 1

x + (x + 1) = $$\frac{5}{6}$$ of x(x + 1)

2x + 1 = $$\frac{5}{6}$$ x(x + 1)

6(2x + 1) = 5x2 + 5x

12x + 6 = 5x2 + 5x

5x2 + 5x - 12x - 6 = 0

5x2 - 7x - 6 = 0

5x2 - 10x + 3x - 6 = 0

5x(x - 2) + 3(x - 2) = 0

(5x + 3)(x - 2) = 0

(5x + 3)(x - 2) = 0

(5x + 3) = 0

x - 2 = 0

for (5x + 3) = 0

5x = -3

x = $$\frac{-3}{5}$$ (Imposible since x is a whole number)

x - 2 = 0

x = 2

x = $$\frac{-3}{5}$$(Impossible since x is a whole number)

x - 2 = 0

x = 2

The numbers are x = 2

x + 1 = 2 + 1

= 3
7
A casting is made up of Copper and Zinc. If 65% of the casting is Zinc and there are 147g of Copper. What is the mass of the casting?
A
320g
B
420g
C
520g
D
620g
correct option: b
%Zinc + %Copper = 100%

65% + %Copper = 100%

%Copper = 100% - 65% = 35%

%Copper = $$\frac{\text{Mass of % Copper}}{\text{Mass of Casting}}$$ x 100%

Mass of Casting = $$\frac{147}{35}$$ x 100%

= 420g
8
Given that P = {x : 1 $$\leq x \leq 6$$}, and Q = {x : 2 $$\leq x \leq 10$$} where x is an integer. Find n(P $$\cap$$)
A
4
B
6
C
8
D
10
correct option: a
P = {1, 2, 3, 4, 5, 6}; Q = {3, 4, 5, 6, 7, 8, 9}

P $$\cap$$ Q) = {2, 4, 5, 6}

n(P $$\cap$$ Q) = 4
9
The sum of 6 and one-third of x is one more than twice x, find x
A
x = 7
B
x = 5
C
x = 3
D
x = 2
correct option: c
6 = $$\frac{1}{3}x$$ = 1 + 2x

6 = 1 = $$\frac{2x}{1} - \frac{x}{3}$$

5 = $$\frac{6x - x}{3} = \frac{5x}{3}$$

5 = $$\frac{5x}{3}$$

3 x 5 = 5x

15 = 5x

x = $$\frac{15}{5}$$

= 3
10
Given that = {x: -2 < x $$\leq$$ 9}, where x is an integer what is n(T)?
A
9
B
10
C
11
D
12
correct option: c
T = {-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9}

n(T) = 11