WAEC Mathematics Past Questions & Answers - Page 187

931.

A point X is on the bearing 342° from a point Y. What is the bearing of Y from X?

A.

342o

B.

252o

C.

198o

D.

162o

Correct answer is D

If x is the bearing 342° from a point y
= 360° - 342° = 18°
The bearing of y from x = 180° - 18° = 162°

932.

Find the mean deviation of 6, 7, 8, 9, 10

A.

1.2

B.

1.5

C.

2

D.

8

Correct answer is A

\(\begin{matrix}
x & x-m & |x-m| \\
6 & -2 & 2 \\
7 & -1 & 1 \\
8 & 0 & 0 \\
9 & 1 & 1 \\
10 & 2 & 2 \\
& & 6
\end{matrix}
\)
Mean deviation\(=\frac{\sum|x-m|}{n}=\frac{6}{5} = 1.2\)

933.

In the diagram, KS is a tangent to the circle centre O at R and ∠ROQ = 80°. Find ∠QRS.

A.

90o

B.

80o

C.

50o

D.

40o

Correct answer is D

QOP = 180 - 100(straight line angle) → 80°
OPQ and OQP are isosceles of 40° each.

∠QRS = ∠RPQ (theorem: angle in the alternate segment are equal)
∠RPQ = 40°
∠QRS = 40°

934.

Given that ξ = {1, 2, 3, . . . . . . ,10}, P= (x : x is prime) and Q = {y : y is odd}, find Pl∩Q

A.

{2}

B.

{1,9}

C.

{315.7}

D.

{4, 6, 8, 10}

Correct answer is B

ξ = {1, 2, 3, . . . . . . ,10}, P= (2, 3, 5, 7) and Q = {1, 3, 5, 9},
Pl∩Q = {1, 4, 6, 8, 9, 10}∩{1, 3, 5, 7, 9} = {1, 9}

935.

Find the sum of the roots of the equation 2x2 + 3x - 9 = 0

A.

-18

B.

-6

C.

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

D.

\(-\frac{3}{2}\)

Correct answer is D

The general quadratic equation
x2 - (sum of roots) x + (product of root) = 0
Comparing with the given equation
2x2 +3x2 - 9 = 0; \(x^2 + \frac{3}{2}x - \frac{9}{2} = 0\\
Sum \hspace{1mm} of \hspace{1mm}roots = -\frac{3}{2}\)