WAEC Mathematics Past Questions & Answers - Page 186

926.

The table above gives the marks scored by a group of students in a test Use the table to answer the Question below
What is the median mark?

A.

1

B.

2

C.

3

D.

4

Correct answer is C

Median = 0, 1, 1, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5
Median mark = \(\frac{3+3}{2} = \frac{6}{2} = 3\)

927.

In the diagram, PQRW is a circle. Line P, V and QR are produced to meet at M, where ∠WMR = 30o and |WM| = |MR| Find the value of x

A.

10o

B.

25o

C.

35o

D.

60o

Correct answer is B

MPQ = PQM = 3x; ∆MPQ
MPQ + PQM + PMQ = 180° 3x + 3x + 30° = 180°
\(6x \times 30° = 180° 6x + 180° - 30°; 6x + 150°\)
\(x = \frac{150}{6} = 25^{\circ}\)

928.

Given that \(\sqrt{128}+\sqrt{18}-\sqrt{K} = 7\sqrt{2}\), find K,

A.

8

B.

16

C.

32

D.

48

Correct answer is C

\(\sqrt{128} +\sqrt{18}-\sqrt{k}=7\sqrt{2}\\
\sqrt{2\times 64}+\sqrt{9\times 2} - \sqrt{k} = 7\sqrt{2}\\
8\sqrt{2} + 3\sqrt{2} - \sqrt{k} = 7\sqrt{2}; 11\sqrt{2} - \sqrt{k} = 7\sqrt{2}\\
-\sqrt{k}=7\sqrt{2}-11\sqrt{2}; -\sqrt{k} = -4\sqrt{2}; \sqrt{k}=4\sqrt{2}\\
=\sqrt{4^2\times 2} = \sqrt{16\times 2}; \sqrt{k}=\sqrt{32}; k = 32\)

929.

Find the average of the first four prime numbers greater than10

A.

20

B.

19

C.

17

D.

15

Correct answer is D

First four prime numbers greater than 10 are 11, 13, 17, 19
The average \(= \frac{11+13+17+19}{4}=15\)

930.

In the diagram, O is the centre of the circle where OS//QR and ∠SOR = 35o

A.

35o

B.

45o

C.

55o

D.

70o

Correct answer is C

∠SOR = ∠ORQ alternate angle.
Also ∠OQR = ∠OQR (Base angle of isosceles)
∠QOR = 108 – 2(35o) = 180 - 70o - 110o ∠QPR = 1/2QOR = 1/2(110o) ∠QPR + 55o (theorem angle at center is twice angle at circumference)