WAEC Mathematics Past Questions & Answers - Page 221

1,101.

Which of the following correctly expresses 48 as a product of prime factors?

A.

3 x 4 x 4

B.

2 x 3 x 8

C.

2 x 2 x 2 x 3 x 4

D.

2 x 2 x 2 x 2 x 3

Correct answer is D

48 = 2 x 2 x 2 x 2 x 3

1,102.

If the simple interest on N2000 after 9 months is N60, at what rate per annum is the interest charged?

A.

\(2\frac{1}{4}\)%

B.

4%

C.

5%

D.

6%

Correct answer is B

\(I = \frac{PRT}{100}\)

\(R = \frac{100I}{PT}\)

\(R = \frac{100 \times 60}{2000 \times \frac{3}{4}}\)

\(R = \frac{6000}{1500}\)

= 4%

1,103.

Solve the equation 3 + 5x - 2x2 = 0

A.

\(-\frac{1}{2},-3\)

B.

2, 3

C.

-2, 3

D.

\(-\frac{1}{2},3\)

Correct answer is D

\(3 + 5x - 2x^2 = 0\\
3 + 6x - x - 2x^2 = 0\\
3(1 + 2x) - x(1 + 2x) = 0\\
(3-x)(1+2x)=0\\
3-x = 0 \hspace{1mm}or \hspace{1mm}1+2x = 0\\
x = 3\hspace{1mm} x = -\frac{1}{2}\\
x = 3 \hspace{1mm}or\hspace{1mm} x =-\frac{1}{2}\)

1,104.

Find the volume (in cm\(^3\)) of the solid shown above

A.

100cm3

B.

150cm3

C.

175cm3

D.

250cm3

Correct answer is C

Total volume = (5 x 5) x 5 + (5 x 5) x 2 

= 125 + 50 

= 175 cm\(^3\)

1,105.

The area of a circle is 38.5cm2. Find its diameter [take \(\pi = \frac{22}{7}\)]

A.

22cm

B.

14cm

C.

7cm

D.

6cm

Correct answer is C

\(\pi r^2 = 38.5\\
\frac{}{} = r^2 = 38.5\\
r^2 = \frac{38.5 \times 7}{22}\\
r = \sqrt{12.25} = 3.5\\
diameter = 2r = 2 \times 3.5 = 7cm\)