WAEC Mathematics Past Questions & Answers - Page 231

1,151.

Which of the following pairs of inequalities is represented on the number line?

A.

\(x<-2 and x\ge1\)

B.

\(x\ge -2 and x>1\)

C.

\(x\le -2 and x\ge1\)

D.

\(x< -2 and x>1\)

Correct answer is C

No explanation has been provided for this answer.

1,152.

Amina had m mangoes. She ate 3 and shared the remainder equally with her brother Uche. Each had at least 10. Which of the following inequalities represents the statements above.

A.

\(\frac{m}{2}-3\le 10\)

B.

\(\frac{m}{2}-3\ge 10\)

C.

\(\frac{m-3}{2}\ge10\)

D.

\(\frac{m-3}{2}\le10\)

Correct answer is C

Total number of mangoes = m

Amina ate 3 mangoes \(\implies\) Remainder = m - 3

Shared equally with Uche \(\implies \frac{m - 3}{2}\)

\(\frac{m - 3}{2} \geq 10\)

1,153.

Water flows from a tap into cylindrical container at the rate 5πcm\(^3\) per second. If the radius of the container is 3cm, calculate the level of water in the container at the end of 9 seconds.

A.

2cm

B.

5cm

C.

8cm

D.

15cm

Correct answer is B

Volume of water after 9 seconds = \(5\pi \times 9 = 45\pi cm^3\)

Volume of cylinder = \(\pi r^2 h\)

\(\therefore \pi r^2 h = 45\pi\)

\(\pi \times 3^2 \times h = 45\pi\)

\(\implies 9h = 45 \)

\(h = 5 cm\)

(where h = height of the water after 9 secs)

1,154.

The height and base of a triangle are in ratio 1:3 respectively. If the area of the triangle is 216 cm\(^2\), find the length of the base.

A.

24cm

B.

36cm

C.

72cm

D.

144cm

Correct answer is B

Area = \(\frac{1}{2} \times base \times height\)

\(height : base = 1 : 3\)

\(\implies base = 3 \times height\)

Let height = h;

Area = \(\frac{1}{2} \times 3h \times h = 216\)

\(3h^2 = 216 \times 2 = 432\)

\(h^2 = \frac{432}{3} = 144\)

\(h = \sqrt{144} = 12.0 cm\)

\(\therefore base = 3 \times 12 = 36 cm\)

1,155.

A car travel at x km per hour for 1 hour and at y km per hour for 2 hours. Find its average speed

A.

\(\frac{2x + 2y}{3}kmh^{-1}\)

B.

\(\frac{x + y}{3}kmh^{-1}\)

C.

\(\frac{x + 2y}{3}kmh^{-1}\)

D.

\(\frac{2x + y}{3}kmh^{-1}\)

Correct answer is C

Travelled x km/h for 1 hour \(\therefore\) traveled x km in the first hour.

Traveled y km/h for 2 hours \(\therefore\) traveled 2y km in the next 2 hours.

Average speed = \(\frac{x + 2y}{1 + 2}\)

= \(\frac{x + 2y}{3} kmh^{-1}\)