WAEC Past Questions and Answers - Page 2430

12,146.

The diagram shows a circle centre O. if <STR = 29 and <RST = 45, calculate the value of <STO

A.

12\(^o\)

B.

15\(^o\)

C.

29\(^o\)

D.

34\(^o\)

Correct answer is A

SRT = 180 - (46 + 29) sum of < s in a

= 180 - 75

= 105

SOT = 2 x 46 < at the centre is twice all the circle = 92

RTO = 180 - (96 + 43)

= 41

STO = 41 - 29

= 12\(^o\)

12,147.

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)

12,148.

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}\)

12,149.

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

12,150.

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