WAEC Past Questions and Answers - Page 2957

14,781.

From the equation whose roots are x = \(\frac{1}{2}\) and -\(\frac{2}{3}\)

A.

6x2 - x + 2 = 0

B.

6x2 - x - 2 = 0

C.

6x2 + x + 2 = 0

D.

6x2 + x - 2 = 0

Correct answer is D

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

expand (x - \(\frac{1}{2}\))(x + \(\frac{2}{3}\)) = 0

x(x + \(\frac{2}{3}\)) - \(\frac{1}{2}(x + \frac{2}{3}\)) = 0

x2 + \(\frac{4x - 3x}{6} - \frac{2}{6} = 0\)

\(x^2 + \frac{x}{6} - 2 = 0\)

6x2 + x - 2 = 0

14,782.

If the efficiency of a transformer is 100%, which of the following equations would be correct? 
 

A.

N\(_p\)E\(_p\) = N\(_s\)E\(_s\)

B.

N\(_s\)I\(_p\)= N\(_p\)I\(_s\)

C.

N\(_s\)I\(_s\) = N\(_p\)I\(_p\)

D.

I\(_p\)E\(_s\) = I\(_s\)E\(_p\)

Correct answer is D

No explanation has been provided for this answer.

14,783.

The cross section section of a uniform prism is a right-angled triangle with sides 3cm. 4cm and 5cm. If its length is 10cm. Calculate the total surface area

A.

142cm2

B.

132cm2

C.

122cm2

D.

112cm2

Correct answer is B

A prism has 3 rectangular faces and 2 triangular faces and 2 rectangular faces = 10(3 + 4 + 5) = 120

Area of triangular faces = \(\sqrt{s(s - a) (s - b) (s - c)}\)

where s = \(\frac{a + b + c}{2}\)

= \(\frac{3 + 4 + 5}{2}\)

= \(\frac{12}{2}\)

= 6

Area of \(\bigtriangleup\) = \(\sqrt{6(6 - 30(6 - 4)(6 - 5)}\)

= \(\sqrt{6 \times 3 \times 2 \times 1}\) = 6

Area of triangle faces = 2 x 6 = 12cm2

Total surface area = Area of rectangular face + Area of \(\bigtriangleup\) = 120 + 12

= 132cm2

14,784.

Esther was facing S 20° W. She turned 90° in the clock wise direction. What direction is she facing?

A.

N 70o W

B.

S 70o W

C.

N 20o W

D.

S 20o E

Correct answer is A

The bearing S 20° W is equivalent to a bearing of 200°.

Moving clockwise 90° ⇒ 200° + 90°

= 290°

This is equivalent to N 70° W.

14,785.

Which of the following statements about a moving object is correct?

A.

When accelerating, the resultant force acting on it must be equal to zero.

B.

There must always be a non-zero resultant force acting on it.

C.

At a steady velocity, the resultant force acting on it must be equal to zero

D.

At a steady velocity, the air resistance must be equal to zero.

Correct answer is C

No explanation has been provided for this answer.