2005 - WAEC Mathematics Past Questions and Answers - page 5
41
XOY is a real sector of a circle center O of radius 3.5cm which subtends an angle of 144o at the center. Calculate, in term of ϖ, the area of the sector
A
1.4ϖcm2
B
2.8ϖcm2
C
4.9ϖcm2
D
9.8ϖcm2
correct option: c
Area of a sector \(=\frac{\theta}{360}\times \pi r^2\
\left(\frac{144}{360}\times \pi \times \frac{3.5}{1} \times 3.5\right)cm^2 = 4.9\pi cm^2\)
Users' Answers & Comments\left(\frac{144}{360}\times \pi \times \frac{3.5}{1} \times 3.5\right)cm^2 = 4.9\pi cm^2\)
42
A rectangular packet has inner dimension 16cm by 12cm by 6cm. How many cubes of sugar of side 2cm can be neatly packed into the packet?
A
90
B
144
C
150
D
288
correct option: b
Volume of rectangular packet = (16 x 12 x 6)cm3 = 1152cm3. Volume of cube of sugar = 2 x 2 x 2 = 8cm
∴ The number of cubes f sugar \(=\frac{1152}{8}=144\)
Users' Answers & Comments∴ The number of cubes f sugar \(=\frac{1152}{8}=144\)
43
If \(y \alpha \frac{1}{x^2}\) and \(y = 1\frac{1}{4}\) when x = 4, find the value of y when \(x = \frac{1}{2}\)
A
\(2\frac{1}{2}\)
B
5
C
10
D
80
correct option: d
\(y \propto \frac{1}{x^2} \Rightarrow y = \frac{k}{x^2} \Rightarrow k = yx^2\
k = 1\frac{1}{4} \times 4^2 \Rightarrow k=\frac{5}{4}\times \frac{16}{1}=20\
∴y = 20 \div \left(\frac{1}{2}\right)^2=20\times \frac{4}{1}=80\)
Users' Answers & Commentsk = 1\frac{1}{4} \times 4^2 \Rightarrow k=\frac{5}{4}\times \frac{16}{1}=20\
∴y = 20 \div \left(\frac{1}{2}\right)^2=20\times \frac{4}{1}=80\)
44
Ladi sold a car for N84,000 at a loss of 4%. How much did ladi buy the car
A
80,500
B
80,640
C
87,360
D
87,500
correct option: d
The car was sold at 96% ---- N84,000.00
The price of the car is 100% ---- ?
\(\frac{100}{96} \times \frac{84,000}{1}; 25 \times 10,500 = 87,500 \)
Users' Answers & CommentsThe price of the car is 100% ---- ?
\(\frac{100}{96} \times \frac{84,000}{1}; 25 \times 10,500 = 87,500 \)
45
The monthly salary of a man increased from N2,700 to N3,200. Find the percentage increase
A
10%
B
15%
C
15.6%
D
18.5%
correct option: d
\(\% increase = \frac{Increase}{initial\hspace{1mm} salary}\times 100\%\
Increase=N3,200 - N2,700 = N500\
Initial \hspace{1mm} salary=N2,700.00=\frac{N500}{N2,700}\times 100\% = 18.5\%\)
Users' Answers & CommentsIncrease=N3,200 - N2,700 = N500\
Initial \hspace{1mm} salary=N2,700.00=\frac{N500}{N2,700}\times 100\% = 18.5\%\)
46
In the diagram, O is the center of the circle, ∠MON = 80o, ∠LMO = 10o and ∠LNO = 15o. Calculate the value of x
A
40o
B
50o
C
55o
D
75o
correct option: c
Reflex + ∠OML + ∠ONL + ∠NLM = 360
280o + 10o + 15o + x = 360o => 305o + xo = 360o
x = 360o - 305o = 55o
Users' Answers & Comments280o + 10o + 15o + x = 360o => 305o + xo = 360o
x = 360o - 305o = 55o
47
The figure shows a quadrilateral PQRS having equal sides and opposite sides parallel. The diagonals PR and QS intersect perpendicularly at O, Which of the following statements cannot be correct
A
|PO|=|RO|
B
PQR is an equilateral triangle
C
PQRX is a parallelogram
D
There are two lines of symmetry
correct option: b
Users' Answers & Comments