WAEC Mathematics Past Questions & Answers - Page 112

556.

Make p the subject of the relation: q = \(\frac{3p}{r} + \frac{s}{2}\)

A.

p = \(\frac{2q - rs}{6}\)

B.

p = 2qr - sr - 3

C.

p = \(\frac{2qr - s}{6}\)

D.

p = \(\frac{2qr - rs}{6}\)

Correct answer is D

q = \(\frac{3p}{r} + \frac{s}{2}\)

q = \(\frac{6p + rs}{2r}\)

6p + rs = 2qr

6p = 2qr - rs

p = \(\frac{2qr - rs}{6}\)

557.

Simplify: \(\frac{54k^2 - 6}{3k + 1}\)

A.

6(1 - 3k2)

B.

6(3k2 - 1)

C.

6(3k - 1)

D.

6(1 - 3k)

Correct answer is C

\(\frac{54k^2 - 6}{3k + 1} = \frac{6(9k^2 - 1)}{3k + 1}\)

= \(\frac{6(3k + 1) - (3k - 1)}{3k + 1}\)

= 6(3k - 1)

558.

Solve for x in the equation; \(\frac{1}{x} + \frac{2}{3x} = \frac{1}{3}\)

A.

5

B.

4

C.

3

D.

1

Correct answer is A

\(\frac{1}{8} + \frac{2}{3x} = \frac{1}{3}\)

= \(\frac{1}{2}\)

\(\frac{5}{3x} = \frac{1}{3}\)

3x = 15

x = \(\frac{15}{3}\)

= 5

559.

If N2,500.00 amounted to N3,50.00 in 4 years at simple interest, find the rate at which the interest was charged

A.

5%

B.

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

C.

8%

D.

10%

Correct answer is D

A = 3,500, P = N2,500

A = P + I

But I = N3,500 - N2,500

I = N1,000

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

N1,000 = \(\frac{2.500 \times R \times 4}{100}\)

1000 = 100R

R = \(\frac{1000}{100}\)

= 10%

560.

Mr. Manu travelled from Accra to Pamfokromb a distance of 720km in 8 hours. What will be his speed in m/s?

A.

25m/s

B.

150m/s

C.

250m/s

D.

500m/s

Correct answer is A

\(\frac{720 \times 1000}{8 \times 60 \times 60}\) = \(\frac{20 \times 10}{8}\)

= \(\frac{200}{8}\)

= 25 m/s