2007 - WAEC Mathematics Past Questions and Answers - page 2
11
If x =3, y = 2 and z = 4 what is the value of \(3x^{2}-2y+z\)
A
17
B
27
C
35
D
71
12
Solve the simultaneous equation: x+y=2 and 3x-2y=1
A
x=2 and y=1
B
x=1 and y=1
C
x=1 and y=2
D
x=-1 and y=1
correct option: b
x + y = 2 --- eqn I
3x - 2y = 1 --- eqn II
Multiply eqn by 2
2x + 2y = 2 --- eqn III
Subtract eqn II from eqnI
5x = 5 => x = 1
Substitute 1 for x in eqn 1
1 + y = 2 => y = 1
Users' Answers & Comments3x - 2y = 1 --- eqn II
Multiply eqn by 2
2x + 2y = 2 --- eqn III
Subtract eqn II from eqnI
5x = 5 => x = 1
Substitute 1 for x in eqn 1
1 + y = 2 => y = 1
13
If \(8^{x+1}=\frac{1}{4}\), find x
A
\(-\frac{5}{3}\)
B
-1
C
\(-\frac{1}{3}\)
D
\(\frac{1}{3}\)
correct option: a
\(8^{x+1}=\frac{1}{4}\
2^{3(x+1)}=2^{-2}\Rightarrow 3(x+1)=-2\Rightarrow 3x+3=-2\
3x=-5\Rightarrow x=\frac{5}{3}\)
Users' Answers & Comments2^{3(x+1)}=2^{-2}\Rightarrow 3(x+1)=-2\Rightarrow 3x+3=-2\
3x=-5\Rightarrow x=\frac{5}{3}\)
14
The area of a square field is 110.25m2. Find the cost of fencing it round at N75.00 per meter square
A
N1,575.00
B
N3,150.00
C
N4,734.30
D
N8,268.75
15
A chord of length 6cm is drawn in a circle of radius 5cm. Find the distance of the chord from the center of the circle
A
2.5cm
B
3.0cm
C
3.5cm
D
4.0cm
correct option: d
\(5^{2}=3^{2}+x^{2}\
25-9=x^{2}\
16=x^{2}\Rightarrow x=4.0\)
Users' Answers & Comments25-9=x^{2}\
16=x^{2}\Rightarrow x=4.0\)
16
A sector of a circle of radius 14cm containing an angle 60o is folded to form a cone. Calculate the radius of the base of the cone.
A
\(5\frac{1}{2}cm\)
B
\(4\frac{2}{3}cm\)
C
\(3\frac{1}{2}cm\)
D
\(2\frac{1}{3}cm\)
correct option: d
\(r=\frac{\theta \times l}{360^{\circ }}\
r=?, \theta =60^{\circ }\), l = radius of the orginal sector of a circle = 14cm
\(r=\frac{60\times 14}{360}=\frac{7}{3}=2\frac{1}{3}cm\)
Users' Answers & Commentsr=?, \theta =60^{\circ }\), l = radius of the orginal sector of a circle = 14cm
\(r=\frac{60\times 14}{360}=\frac{7}{3}=2\frac{1}{3}cm\)
17
IN the diagram, |LN| = 4cm, LNM = 90o and tan y = 2/3. What is the area of the ∆LMN?
A
24cm2
B
12cm2
C
10cm2
D
6cm2
correct option: b
\(tan \hspace{1mm}y = \frac{opp}{adj}=\frac{2}{3}\Rightarrow \frac{2}{3}=\frac{
LN}{MN}=\frac{4}{MN}\
∴ MN = \frac{12}{2}=6\
Area \hspace{1mm}of \hspace{1mm}\Delta LMN = \frac{1}{2}\times MN\times LN=\frac{1}{2}\times 6\times 4=12cm\)
Users' Answers & CommentsLN}{MN}=\frac{4}{MN}\
∴ MN = \frac{12}{2}=6\
Area \hspace{1mm}of \hspace{1mm}\Delta LMN = \frac{1}{2}\times MN\times LN=\frac{1}{2}\times 6\times 4=12cm\)
18
Evaluate(111two)2 and leave your answer in base 2.
A
111001two
B
110001two
C
101001two
D
10010two
correct option: b
Users' Answers & Comments19
Find the LCM of 23 x 3 x 52, 2 x 32 x 5 and 23 x 33 x 5
A
22 x 33 x 52
B
23 x 33 x 5
C
22 x 32 x 52
D
23 x 33 x 52
correct option: d
23 x 3 x 52
2 x 32 x 5
22 x 33 x 5
The L.C.M = 22 x 33 x 52
Users' Answers & Comments2 x 32 x 5
22 x 33 x 5
The L.C.M = 22 x 33 x 52
20
Simplify(0.3 x 105) \(\div\) (0.4 \(\times\) 107), leaving you answer in the standard form.
A
7.5 x 10-4
B
7.5 x 10-3
C
7.5 x 10-2
D
7.5 x 10-1
correct option: b
\(\frac{0.3 \times 10^5}{0.4 \times 10^7} = \frac{3 \times 10^{-1} \times 10^{5}}{4 \times 10^{-1} \times 10^7}\)
\(\frac{3 x 10^4}{4 x 10^4}\)
\(\frac{3}{4}\) x 104-6 = 0.75 x 10-2
= 7.5 x 10-3
Users' Answers & Comments\(\frac{3 x 10^4}{4 x 10^4}\)
\(\frac{3}{4}\) x 104-6 = 0.75 x 10-2
= 7.5 x 10-3