WAEC Mathematics Past Questions & Answers - Page 56

276.

Express 0.0000407, correct to 2 significant figures

A.

0.0

B.

0.00004

C.

0.000041

D.

0.0000407

Correct answer is C

0.0000407 to 2 s.f 0.000041 (2 s.f)

277.

The graph of y = x\(^2\) and y = x intersect at which of these points?

A.

(0,0), (1,1)

B.

(0,0), (0,1)

C.

(1, 0), (0, 0)

D.

(0, 0) (0, 0)

Correct answer is A

y = x\(^2\) ....(1)

y = x ......(2)

y = y

x\(^2\) - x

x\(^2\) - x = 0

x(x - 1) = 0

x = 0 or x - 1 = 0

x = 0 or x = 1

when x = 0, y = 0\(^2\) = 0

when x = 1, y = 1\(^2\) = 1

Hence; the two graphs interest at (0, 0) and (1, 1)

278.

M and N are two subsets of the universal set (U). If n(U) = 48, n(M) = 20, n(N) = 30 and n(MUN) = 40, find n(M \(\cap\) N)

A.

18

B.

20

C.

30

D.

38

Correct answer is D

Let n(M \(\cup\) N \) = x

Then 20 - x + x + 30

- x = n(M \(\cup\) N)

50 - x = 40

50 - 40 = x

10 = x

x = 10

Hence, n(M \(\cup\N)' = 8  + (20 - 10) + (30 + 10)

= 8 + 10 + 20

= 38

279.

The diagonals of a rhombus WXYZ intersect at M. If |MW| = 5cm and |MX| = 12cm, calculate its perimeter

A.

42cm

B.

48cm

C.

52cm

D.

60cm

Correct answer is C

Let the length of a side of the rhombus be n

Then, n\(^2\) = 5\(^2\) + 12\(^2\)

= 25 + 144 = 169

n = \(\sqrt{169}\)

= 13cm

Hence, perimeter of rhombus = 4n = 4 x 13

= 52cm

280.

Given that Y is 20cm on a bearing of 300\(^o\) from x, how far south of y is x?

A.

10cm

B.

15cm

C.

25cm

D.

30cm

Correct answer is A

In \(\bigtriangleup\)YSC, sin 30\(^o\) = \(\frac{YS}{20}\)

|YS| = 20 sin 30\(^o\)

= 20 x 0.5

10m