WAEC Mathematics Past Questions & Answers - Page 49

241.

Fig. 1 and Fig. 2 are the addition and multiplication tables respectively in modulo 5. Use these tables to solve the equation (n \(\oplus 4\))

A.

1

B.

2

C.

3

D.

4

Correct answer is C

(n \(\oplus\) 4) \(\oplus\) 3 = 0 (mod 5)

(3 \(\oplus\) 4) \(\oplus\) 3

12 \(\oplus\) 3 = 15 (mod 5)

(5 x 3 + 0) = 0 (mod 5)

242.

A circular pond of radius 4m has a path of width 2.5m round it. Find, correct to two decimal places, the area of the path. [Take\(\frac{22}{7}\)]

A.

7.83\(m^2\)

B.

32.29\(m^2\)

C.

50.29\(m^2\)

D.

82.50\(m^2\)

Correct answer is D

Area of path = Area of (pond+path) - Area of pond

The area of the pond with the path: The radius = (4 + 2.5)m = 6.5m

Area = \(\pi \times r^{2}\) = \(\frac{22}{7} \times 6.5^{2} \approxeq 132.79m^{2}\)

Area of the pond = \(\frac{22}{7} \times 4^{2} \approxeq 50.29m^{2}\)

 Area of the path  = (132.79 - 50.29)m^{2} = 82.50m^{2}\)

243.

Calculate the variance of 2, 3, 3, 4, 5, 5, 5, 7, 7 and 9

A.

2.2

B.

3.4

C.

4.0

D.

4.2

Correct answer is D

x = \(\frac{2 + 3 + 3 + 4 + 5 + 5+ 5+ 7 + 7 + 9}{10}\)

=\(\frac{50}{10}\)

= 5

Variance = \(\frac{\sum{(x - x})^2}{N}\)

\(\frac{9 + 4+ 4+ 1 + 4 + 4 + 16}{10}\)

= \(\frac{42}{10}\)

= 4.2

244.

If the simple interest on a certain amount of money saved in a bank for 5 years at 2\(\frac{1}{2}\)% annum is N500.00, calculate the total amount due after 6 years at the same rate

A.

N2,500.00

B.

N2,600.00

C.

N4,500.00

D.

N4,600.00

Correct answer is D

P = \(\frac{100l}{RT} = \frac{100 \times 500}{5 \times 2.5} = \frac{50,000}{12.5}\)

= 4,000

Annual interest is \(\frac{500}{5}\) = 100

for 6 year = 4,000 + 100 + 100 + 100 + 100 + 100 + 100

= N 4,600

245.

Two bottles are drawn with replacement from a crate containing 8 Coke, 12 Fanta, and 4 Sprite bottles. What is the probability that the first is coke and the second is not coke?

A.

\(\frac{1}{12}\)

B.

\(\frac{1}{6}\)

C.

\(\frac{2}{9}\)

D.

\(\frac{3}{8}\)

Correct answer is C

Total = 8 + 12 + 4

= 24

\(\frac{8}{24} \times (\frac{12}{24} + \frac{4}{24}\))

= \(\frac{1}{3} \times (\frac{1}{2} + \frac{1}{6}\))

= \(\frac{1}{3} \times \frac{3 + 1}{6}\)

\(\frac{1}{3} \times \frac{4}{6} = \frac{2}{9}\)