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WAEC Mathematics Past Questions & Answers - Page 182

906.

A bag contains 3 red and 2 white identical balls. lf 2 balls are picked at random from the bag, one after the other and with replacement, find the probability that they are of different colours

$\frac{36}{625}$

$\frac{16}{625}$

$\frac{12}{25}$

$\frac{13}{25}$

View answer & explanation

Correct answer is C

Prob(RW or WR) = Prob(RW) + Prob(WR)
$Prob(R) = \frac{3}{5}:Prob(W) = \frac{2}{5}\\ Prob(RW\hspace{1mm}or\hspace{1mm}WR)=\frac{3}{5}\times\frac{2}{5}+\frac{2}{5}\times \frac{3}{5}\\ \frac{6}{25}+\frac{6}{25}=\frac{12}{25}$

907.

A Cooperative Society, charges an interest of 5¹/₂% per annum on any amount borrowed by its members. If a member borrows N125,000, how much does he pay back after one year?

N136875

N131,875

N126750

N126250

View answer & explanation

Correct answer is B

The rate of interest charge = 5¹/₂% p.a
The amount borrowed = N125, 000:00
Interest charge $=\frac{11}{200} of N125,000\\ = 11 \times N625.00 = N6,875.00$
The amount refunded by the member with interest charge by the cooperative society
N125,000+N6,875.00 = N131,875.00

908.

Given that p = 2, q = -5 and r = - 4, evaluate 3p² - q² - r³

101

-27

View answer & explanation

Correct answer is C

3(2)² - (-5)² - (-4)³
3(4) – (25) – (-64); 12 – 25 + 64 = 51

909.

The sides of two cubes are in the ratio 2:5. What is the ratio of their volumes?

4:5

8:15

6:125

8:125

View answer & explanation

Correct answer is D

The ratio of the two cubes = 2:5
Volume of the two cubes = 2 $^3$ : 5 $^3$ = 8 : 125

910.

Which of the following is/are true? In a plane, the locus of points

I. Equidistant from a straight line is a circle radius d where d is the distance between the point and the straight line.
II Equidistant from two given points P and Q is a circle of radius |PQ|.

III Equidistant from two points is the perpendicular bisector of the line joining the two points.

I only

II only

III only

I, II and III

View answer & explanation

Correct answer is C

No explanation has been provided for this answer.