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Mathematics
WAEC / WASSCE 2013
Number and Numeration
Solution
If \(\sqrt{50} - K\sqrt{8} = \frac{2}{\sqrt{2}}\), find K
A
-2
B
-1
C
1
D
2
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
\(\sqrt{50} - K\sqrt{8} = \frac{2}{\sqrt{2}}\)
\(\sqrt{50} - \frac{2}{\sqrt{2}}\) = K\(\sqrt{8}\)
= \(\sqrt{2} \times 25 - \frac{2}{\sqrt{2}}\)
= K \(\sqrt{4 \times 2}\)
\(\frac{5\sqrt{2}}{1} - \frac{2}{\sqrt{2}}\) = 2K\(\sqrt{2}\)
\(\frac{5\sqrt{4} - 2}{\sqrt{2}} = 2K\sqrt{2}\)
\(\frac{10 - 2}{\sqrt{2}} = 2K \sqrt{2}\)
\(\frac{8}{\sqrt{2}} = \frac{2K\sqrt{2}}{1}\)
= 2k\(\sqrt{2} \times \sqrt{2}\) = 8
2k \(\sqrt{4}\) = 8
2k x 2 = 8
4k = 8
k = \(\frac{8}{4}\)
k = 2
Source: Myschool Past Questions Archive (Record #36854)
Mathematics
WAEC / WASSCE 2013
Number and Numeration
Solution
A sales boy gave a change of N68 instead of N72. Calculate his percentage error
A
4%
B
5\(\frac{5}{9}\)%
C
5\(\frac{15}{17}\)%
D
7%
medium Difficulty
Verified Correct Answer: Option B
Step-by-Step Mathematical Solution
% error = \(\frac{error}{\text{actual value}} \times 100\)
error = N72 - N68 = 4
actual value = N72
%error = \(\frac{4}{72} \times 100\)
= \(\frac{100}{18} = \frac{50}{9}\) = 5\(\frac{5}{9}\)%
Source: Myschool Past Questions Archive (Record #36857)
Mathematics
WAEC / WASSCE 2013
Number and Numeration
Solution
Four oranges sell for Nx and three mangoes sell for Ny. Olu bought 24 oranges and 12 mangoes. How much did he pay in terms of x and y?
A
N94x + 6y)
B
N(6x + 4y)
C
N(24x + 12y)
D
N(12x + 24y)
medium Difficulty
Verified Correct Answer: Option B
Step-by-Step Mathematical Solution
4 oranges sell for Nx, 1 orange will sell for \(\frac{Nx}{4}\)
24 oranges will sell for: \(\frac{Nx}{4} \times 24\) = n6x
3 mangoes sell for Ny, 1 mango will sell for \(\frac{Ny}{3}\)
12 mangoes will sell for \(\frac{Ny}{3} \times 12\) = 4Ny
total money pay N6x + N4y = N(6x + 4y)
Source: Myschool Past Questions Archive (Record #36858)
Mathematics
WAEC / WASSCE 2013
Number and Numeration
Solution
Simplify: \(\frac{x^2 - y^2}{(x + y)^2} \div \frac{(x - y)^2}{(3x + 3y)}\)
A
\(\frac{x - y}{3}\)
B
x + y
C
\(\frac{3}{x - y}\)
D
x - y
medium Difficulty
Verified Correct Answer: Option C
Step-by-Step Mathematical Solution
\(\frac{x^2 - y^2}{(x + y)^2} \div \frac{(x - y)^2}{(3x + 3y)}\)
\(\frac{(x + y)(x - y)}{(x + y)(x + y)}\div \frac{(x - y)(x - y)}{3(x + y)}\)
= \(\frac{3}{x - y}\)
Source: Myschool Past Questions Archive (Record #36860)
Mathematics
WAEC / WASSCE 2013
Number and Numeration
Solution
If x = 64 and y = 27, evaluate: \(\frac{x^{\frac{1}{2}} - y^{\frac{1}{3}}}{y - x^{\frac{2}{3}}}\)
A
2\(\frac{1}{5}\)
B
1
C
\(\frac{5}{11}\)
D
\(\frac{11}{43}\)
medium Difficulty
Verified Correct Answer: Option C
Step-by-Step Mathematical Solution
\(\frac{x^{\frac{1}{2}} - y^{\frac{1}{3}}}{y - x^{\frac{2}{3}}}\)
substitute x = 64 and y = 27
\(\frac{64^{\frac{1}{2}} - 27^{\frac{1}{3}}}{27 - 64^{\frac{2}{3}}} = \frac{\sqrt{64} - 3\sqrt{27}}{27 - (3\sqrt{64})^2}\)
= \(\frac{8 - 3}{27 - 16}\)
= \(\frac{5}{11}\)
Source: Myschool Past Questions Archive (Record #36864)
Mathematics
WAEC / WASSCE 2013
Number and Numeration
Solution
A cube and cuboid have the same base area. The volume of the cube is 64cm\(^3\) while that of the cuboid is 80cm\(^3\). Find the height of the cuboid
A
1cm
B
3cm
C
5cm
D
6cm
medium Difficulty
Verified Correct Answer: Option C
Step-by-Step Mathematical Solution
Volume of a cube with side a cm = a\(^3\)
a\(^3\) = 64 \(\implies\) a = 4cm
Base area of a cube = a\(^2\)
= 4\(^2\)
= 16 cm\(^2\)
\(\implies\) Base area of the cuboid = 16 cm\(^2\)
Volume of cuboid = Base area x height
80 = 16 x h
h = \(\frac{80}{16}\)
= 5 cm
Source: Myschool Past Questions Archive (Record #36870)
Mathematics
WAEC / WASSCE 2013
Number and Numeration
Solution
An object is 6m away from the base of a mast. The angle of depression of the object from the top pf the mast is 50o, Find, correct to 2 decimal places, the height of the mast
A
8.60m
B
7.51m
C
7.15m
D
1.19m
medium Difficulty
Verified Correct Answer: Option C
Step-by-Step Mathematical Solution
Tan 50o = \(\frac{h}{6}\)
h = 6 tan 50
= 6 x 1.1917
= 7.1505
= 7.15
Source: Myschool Past Questions Archive (Record #36877)
Mathematics
WAEC / WASSCE 2013
Number and Numeration
Solution
If 2 log x (3\(\frac{3}{8}\)) = 6, find the value of x
A
\(\frac{3}{2}\)
B
\(\frac{4}{3}\)
C
\(\frac{2}{3}\)
D
\(\frac{1}{2}\)
medium Difficulty
Verified Correct Answer: Option A
Step-by-Step Mathematical Solution
2 log x (3\(\frac{3}{8}\)) = 6(divide both sides by 2)
\(\frac{2 log_x(3 \frac{3}{8})}{2} = \frac{6}{2}\)
\(\log_x \frac{27}{8} = 3\)
\(\frac{27}{8} = x^3\)
\(x^3 = \frac{27}{8}\)
x = \(\sqrt{\frac{27}{8}}\)
= (\(\frac{27}{8}\))\(\frac{1}{3}\)
= \(\frac{(3^3)^{\frac{1}{3}}}{(2^3)^{\frac{1}{3}}}\)
= \(\frac{3}{2}\)
Source: Myschool Past Questions Archive (Record #36882)
Mathematics
WAEC / WASSCE 2013
Number and Numeration
Solution
If p = (y : 2y \(\geq\) 6) and Q = (y : y -3 \(\leq\) 4), where y is an integer, find p\(\cap\)Q
A
{3, 4}
B
{3, 7}
C
{3, 4, 5, 6, 7}
D
{4, 5, 6}
medium Difficulty
Verified Correct Answer: Option C
Step-by-Step Mathematical Solution
p = (y : 2y \(\geq\) 6)
2y \(\geq\) 6
y \(\geq \frac{6}{2}\)
y = \(\geq\) 3
and Q = (y : y -3 \(\leq\) 4)
y - 3 \(\leq\) 4
y \(\leq\) 4 + 3
y \(\leq\) 7
therefore p = {3, 4, 5, 6, 7} and Q = {7, 6, 5, 4, 3....}
P\(\cap\)Q = {3, 4, 5, 6, 7}
Source: Myschool Past Questions Archive (Record #36883)
Mathematics
WAEC / WASSCE 2013
Number and Numeration
Solution
If y varies directly as the square root of (x + 1) and y = 6 when x = 3, find x when y = 9
A
8
B
7
C
6
D
5
medium Difficulty
Verified Correct Answer: Option A
Step-by-Step Mathematical Solution
y \(\alpha\) \sqrt{x + 1}\), y = k\sqrt{x + 1}\)
6 = k\(\sqrt{3 + 1}\)
6 = k\(\sqrt{4}\)
6 = 2k
k = \(\frac{6}{2}\) = 3
y = \(\sqrt{(x + 1)}\)
9 = 3\(\sqrt{(x + 1)}\)(divide both side by 3)
\(\frac{9}{3}\) = \(\frac{3\sqrt{x + 1}}{3}\)
3 = \(\sqrt{x + 1}\)(square both sides)
9 = x + 1
x = 9 - 1
x = 8
Source: Myschool Past Questions Archive (Record #36885)
Mathematics
WAEC / WASSCE 2013
Number and Numeration
Solution
The graph of the relation y = x2 + 2x + k passes through the point (2, 0). Find the values of k
A
zero
B
-2
C
-4
D
-8
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
y = x2 + 2x + k at point(2,0) x = 2, y = 0
0 = (2)2 + 2(20 + k)
0 = 4 + 4 + k
0 = 8 + k
k = -8
Source: Myschool Past Questions Archive (Record #36886)
Mathematics
WAEC / WASSCE 2013
Number and Numeration
What is the locus of the point X which moves relative to two fixed points P and M on a plane such that o
A
thebisector of the straight line joining P and M
B
an arc of a circle with PM as a chord
C
the bisector of angle PXM
D
a circle centre X and radius PM
medium Difficulty
Verified Correct Answer: Option B
Step-by-Step Mathematical Solution
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #36887)
Mathematics
WAEC / WASSCE 2013
Number and Numeration
Solution
Express \(\frac{2}{x + 3} - \frac{1}{x - 2}\) as a simple fraction
A
\(\frac{x - 7}{x^2 + x - 6}\)
B
\(\frac{x - 1}{x^2 + x - 6}\)
C
\(\frac{x - 2}{x^2 + x - 6}\)
D
\(\frac{x - 27}{x^2 + x - 6}\)
medium Difficulty
Verified Correct Answer: Option A
Step-by-Step Mathematical Solution
\(\frac{2}{x + 3} - \frac{1}{x - 2}\) = \(\frac{2(x - 2) - (x - 3)}{(x + 3) (x - 2)}\)
= \(\frac{2x - 4 - x - 3}{x^2 - 2x + 3x - 6}\)
= \(\frac{x -7}{x^2 + x - 6}\)
= \(\frac{x - 7}{x^2 + x - 6}\)
Source: Myschool Past Questions Archive (Record #36896)
Mathematics
WAEC / WASSCE 2013
Number and Numeration
Solution
Given that P = x2 + 4x - 2, Q = 2x - 1 and Q - p = 2, find x
A
-2
B
-1
C
1
D
2
medium Difficulty
Verified Correct Answer: Option B
Step-by-Step Mathematical Solution
P = x2 + 4x - 2, Q = 2x - 1
Q - p = 2, (2x - 1) - (x2 + 4x - 2) = 2
2x - 1 - x2 - 4x + 2 = 2
-2x - x2 + 1
-x2 - 2x - 1 = 0
x2 + 2x + 1 = 0
x2 + x + x + 1 = 0
x(x + 1) + 1(x + 1) = 0
(x + 1)(x + 1) = 0
x + 1 = 0 or x + 1 = 0
x = -1 or x = -1
x = -1
Source: Myschool Past Questions Archive (Record #36900)
Mathematics
WAEC / WASSCE 2013
Number and Numeration
Solution
A pyramid has a rectangular base with dimensions 12m by 8m. If its height is 14m, calculate the volume
A
322m3
B
448m3
C
632m2
D
840m2
medium Difficulty
Verified Correct Answer: Option B
Step-by-Step Mathematical Solution
Volume of pyramid = \(\frac{1}{3}\) x base area x height
= \(\frac{1}{3} \times 124 \times 8 \times 14\)
= 4 x 8 x 14 = 448m\(^3\)
Source: Myschool Past Questions Archive (Record #36903)