WAEC Past Questions and Answers - Page 4238

21,186.

What angle represents grown up girls ? Correct to one decimal place

A.

37.5o

B.

26.7o

C.

25.7o

D.

20o

E.

3.75o

Correct answer is B

Total population = 1400 + 550 + 200 + 150 + 400 = 2700

grown up girls = 200

= \(\frac {200}{2700}\) x \(\frac {360}{1}\)

=80/3 = 26.7°

21,187.

Solve the following equation: 6x\(^2\) - 7x - 5 = 0

A.

x = 1/2 or x = -21/2

B.

x = 1/3 or x = 21/2

C.

x = 1 2/3 or x = -1/2

D.

x = 12/3 or x = 1/2

E.

x = 5/6 or x = -1

Correct answer is C

6x\(^2\) - 7x - 5 = 0

6x\(^2\) - 10x + 3x - 5 = 0

2x(3x - 5) + 1(3x - 5) = 0

(2x + 1)(3x - 5) = 0

x = \(\frac{5}{3}\) or x = \(-\frac{1}{2}\)

21,188.

Calculate the surface area of a hallow cylinder which is closed at one end, if the base radius is 3.5cm and the height 8cm.[take π = 22/7]

A.

126.5cm2

B.

165cm2

C.

176cm2

D.

214.5cm2

E.

253.5cm2

Correct answer is D

since it is an open cylinder; r= 3.5cm = 7/2cm
h= 8cm;
S.A = 2πrh + πr 2

= πr(2h + r)
(16 + 3.5); 11 x 19.5 = 214.5cm2

21,189.

In the diagram above, O is the center of the circle. Calculate the length of the chord AB if |OA| = 5cm, |OD| = 3cm and ∠AOD = ∠BOD

A.

3cm

B.

4cm

C.

5cm

D.

8cm

E.

15cm

Correct answer is D

In \(\Delta DOB\), let < DOB = \(\alpha\)

In \(\Delta DOB\), \(5^2 = 3^2 + s^2\)

\(s^2 = 25 - 9 = 16\)

\(s = 4cm\)

\(\sin \alpha = \frac{4}{5}\)

\(\alpha = \frac{< AOB}{2}\)

Length of chord = \(2r \sin (\frac{\theta}{2})\)

|OB| = r = 5cm

L = \(2(5)(\frac{4}{5})\)

= 8 cm

21,190.

Points X and Y are respectively 20km North and 9km East of a point O. What is the bearing of Y from X? Correct to the nearest degree

A.

024o

B.

114o

C.

156o

D.

204o

E.

336o

Correct answer is C

tan\(\theta\) = 9/20 = 0.45

\(\theta\) = tan\(^{-1}\) 0.45 = 24.2°

the bearing of y from x = 180 0 - 0 = 180° - 24.2°

the bearing = 155.8°

\(\approxeq\) 156°