2011 - WAEC Mathematics Past Questions and Answers - page 2
11
From the equation whose roots are x = \(\frac{1}{2}\) and -\(\frac{2}{3}\)
A
6x2 - x + 2 = 0
B
6x2 - x - 2 = 0
C
6x2 + x + 2 = 0
D
6x2 + x - 2 = 0
correct option: d
x = \(\frac{1}{2}\) and x = \(\frac{-2}{3}\)
expand (x - \(\frac{1}{2}\))(x + \(\frac{2}{3}\)) = 0
x(x + \(\frac{2}{3}\)) - \(\frac{1}{2}(x + \frac{2}{3}\)) = 0
x2 + \(\frac{4x - 3x}{6} - \frac{2}{6} = 0\)
\(x^2 + \frac{x}{6} - 2 = 0\)
6x2 + x - 2 = 0
Users' Answers & Commentsexpand (x - \(\frac{1}{2}\))(x + \(\frac{2}{3}\)) = 0
x(x + \(\frac{2}{3}\)) - \(\frac{1}{2}(x + \frac{2}{3}\)) = 0
x2 + \(\frac{4x - 3x}{6} - \frac{2}{6} = 0\)
\(x^2 + \frac{x}{6} - 2 = 0\)
6x2 + x - 2 = 0
12
Simplify \(\frac{\log \sqrt{27}}{\log \sqrt{81}}\)
A
3
B
2
C
\(\frac{3}{2}\)
D
\(\frac{3}{4}\)
correct option: d
\(\frac{\log \sqrt{27}}{\log \sqrt{81}}\) = \(\frac{\log 27\frac{1}{2}}{81\frac{1}{2}}\)
= \(\frac{\log 3\frac{1}{2}}{\log 3^2}\)
\(\frac{\frac{3}{2} \log 3}{2 \log 3} = \frac{3}{2} \div \frac{2}{1}\)
= \(\frac{3}{2} \times \frac{1}{2}\)
= \(\frac{3}{4}\)
Users' Answers & Comments= \(\frac{\log 3\frac{1}{2}}{\log 3^2}\)
\(\frac{\frac{3}{2} \log 3}{2 \log 3} = \frac{3}{2} \div \frac{2}{1}\)
= \(\frac{3}{2} \times \frac{1}{2}\)
= \(\frac{3}{4}\)
13
Which of these angles can be constructed using ruler and a pair of compasses only?
A
115o
B
125o
C
135o
D
145o
correct option: c
Users' Answers & Comments14
The perimeter of a sector of a circle of radius 4cm is (\(\pi + 8\))cm. Calculate the anle of the sector
A
45o
B
60o
C
75o
D
90o
correct option: a
Perimeter of sector = 2r + \(\frac{\theta}{360^o} \times 2\pi r\)
\(\pi + 8 = 2 \times 4 + \frac{\theta}{3360^o} \times 2 \pi \times 4\)
\(\pi + 8 + \frac{\theta}{360^o} \times 8 \pi\)
P + 8 - 8 = \(\frac{\theta \pi}{456o}\)
\(\pi = \frac{\theta \pi}{45^o}\)
\(\theta \pi = 45^o\)
Users' Answers & Comments\(\pi + 8 = 2 \times 4 + \frac{\theta}{3360^o} \times 2 \pi \times 4\)
\(\pi + 8 + \frac{\theta}{360^o} \times 8 \pi\)
P + 8 - 8 = \(\frac{\theta \pi}{456o}\)
\(\pi = \frac{\theta \pi}{45^o}\)
\(\theta \pi = 45^o\)
15
The length of a piece of stick is 1.75m. A girl measured it as 1.80m. Find the percentage error
A
\(\frac{28}{7}\)%
B
\(\frac{29}{7}\)%
C
5%
D
\(\frac{20}{7}\)%
correct option: d
Error = 1.80m - 1.75m = 0.05m
%error = \(\frac{\text{error}}{\text{true measurement}}\) x 100%
Users' Answers & Comments%error = \(\frac{\text{error}}{\text{true measurement}}\) x 100%
16
What is the value of 3 in the number 42.7531?
A
\(\frac{3}{10000}\)
B
\(\frac{3}{1000}\)
C
\(\frac{3}{100}\)
D
\(\frac{1}{10}\)
correct option: c
Users' Answers & Comments17
The height of a cylinder is equal to its radius. If the volume is 0.216 \(\pi m^3\) Calculate the radius.
A
0.46m
B
0.60m
C
0.87m
D
1.80m
correct option: a
volume of cylinder = \(\pi r^2\)h
0.216\(\pi m^3 = \pi \times r^2 \times 1m\)
assumed that h = 1m
0.216 = r2
r2 = 0.216
r = \(\sqrt{0.216}\)
= 0.46
Users' Answers & Comments0.216\(\pi m^3 = \pi \times r^2 \times 1m\)
assumed that h = 1m
0.216 = r2
r2 = 0.216
r = \(\sqrt{0.216}\)
= 0.46
18
The height of a cylinder is equal to its radius. If the volume is 0.216 \(\pi m^3\) Calculate the radius.
A
0.46m
B
0.60m
C
0.87m
D
1.80m
correct option: a
volume of cylinder = \(\pi r^2\)h
0.216\(\pi m^3 = \pi \times r^2 \times 1m\)
assumed that h = 1m
0.216 = r2
r2 = 0.216
r = \(\sqrt{0.216}\)
= 0.46
Users' Answers & Comments0.216\(\pi m^3 = \pi \times r^2 \times 1m\)
assumed that h = 1m
0.216 = r2
r2 = 0.216
r = \(\sqrt{0.216}\)
= 0.46
19
What is the value of 3 in the number 42.7531?
A
\(\frac{3}{10000}\)
B
\(\frac{3}{1000}\)
C
\(\frac{3}{100}\)
D
\(\frac{1}{10}\)
correct option: b
Users' Answers & Comments20
Factorize the expression: am + bn - an - bm
A
(a - b)(m + n)
B
(a - b)(m - n)
C
(a + b)(m - n)
D
(a + b)(m + n)
correct option: b
am + bn - an - bm
am - an - bm + bn
a(m - n) - b(m - n)
(a - b)(m - n)
Users' Answers & Commentsam - an - bm + bn
a(m - n) - b(m - n)
(a - b)(m - n)