WAEC Mathematics Past Questions & Answers - Page 195

971.

Given that x ≅ 0.0102 correct to 3 significant figures, which of the following cannot be the actual value of x?

A.

0.01014

B.

0.01021

C.

0.01015

D.

0.01016

Correct answer is A

option A CANNOT BE BECAUSE THE LAST NUMBER BEFORE 1 CAN ONLY BE ROUNDED DOWN TO ZERO.

972.

Evaluate \((111_{two})^2 - (101_{two})^2\)

A.

10two

B.

100two

C.

1100two

D.

11000two

Correct answer is D

\((111_{2})^2 - (101_{2})^2\)

Difference of two squares

\((111 - 101)(111 + 101)\)

= \((10)(1100)\)

= \(11000_{2}\)

973.

In the diagram, \(P\hat{Q}S = 65^o, R\hat{P}S = 40^o\hspace{1mm}and\hspace{1mm}Q\hat{S}R=20^o\hspace{1mm}, find   P\hat{S}Q\)

A.

85o

B.

60o

C.

55o

D.

45o

Correct answer is C

< QPS = < PRS = 65° (angles in the same segment)

< PSR + 40° + 65° = 180°

< PSR + 105° = 180°

< PSR = 75°

< PSR = < PSQ + < QSR

75° = < PSQ + 20° \(\implies\) < PSQ = 75° - 20° = 55°

974.

Find the values of x for which \( \frac{1}{2x^2 - 13x +15} \) is not defined,

A.

5 or \( \frac{3}{2} \)

B.

1 or \( \frac{15}{13} \)

C.

2 or 15

D.

13 or 15

Correct answer is A

The fraction is undefined when the denominator is equal to zero
\(2x^2 - 13x + 15 = 0\\
2x^2 - 3x - 10x + 15\\
x(2x-3)-5(2x-3) = 0\\
(2x-3)(x-5)=0\\
x = \frac{3}{2} or x = 5\)

975.

Out of 60 members of an Association, 15 are Doctors and 9 are Lawyers. If a member is selected at random from the Association, what is the probability that the member is neither a Doctor Nor a Lawyer

A.

\(\frac{3}{5}\)

B.

\(\frac{9}{10}\)

C.

\(\frac{3}{20}\)

D.

\(\frac{1}{4}\)

Correct answer is A

Member that are neither doctors nor lawyers = 60-(15+9)=36
Probability (Not doctors ad not lawyers) \(=\frac{36}{60}\\
=\frac{6}{10}=\frac{3}{5}\)