WAEC Further Mathematics Past Questions & Answers - Page 29

141.

If the binomial expansion of (1 + 3x)\(^6\) is used to evaluate (0.97)\(^6\), find the value of x. 

A.

0.03

B.

0.01

C.

-0.01

D.

-0.03

Correct answer is C

(1 + 3x )\(^6\) = (0.97)\(^6\) 

1 + 3x = 0.97 

3x = 0.97.1

\(\frac{3x}{3} = \frac{0.03}{3}\)

x = -0.01

142.

In which of the following series can be the formula S = \(\frac{a}{1 - r}\) where a is the first term and r is the common ratio, be used to find the sum of all the terms? 

A.

4 + 8 + 16 + 32 + ...

B.

\(\frac{1}{2}\) + 2 \(\frac{1}{2}\) + 12\(\frac{1}{2}\) + 62 \(\frac{1}{2}\) + ..

C.

\(\frac{4}{81}\) + \(\frac{2}{27}\) + \(\frac{1}{9}\) + \(\frac{1}{6}\) + ...

D.

128 + 64 + 32 + 16 + ...

Correct answer is D

No explanation has been provided for this answer.

143.

A stone was dropped from the top of a building 40m high. Find, correct to one decimal place, the time it took the stone to reach the ground. [Take g = 9.8ms\(^{-2}\)]

A.

2.9.seconds

B.

2.8 seconds

C.

2.6 seconds

D.

1.4 seconds

Correct answer is A

s = \(\frac{1}{2}gt^2\) 

40 = \(\frac{1}{2} \times 9.8 \times t^2\)

\(\frac{80}{9.8} = t^2\)

t = \(\sqrt{8.16326}\)

t  2.9 secs

144.

Given that F = 3i - 12j, R = 7i + 5j and N = pi + qj are forces acting on a body, if the body is in equilibrium. find the values of p and q.

A.

p=-10, q=7

B.

p=-10, q=-7

C.

p=10, q=- 7

D.

p-10, q=7

Correct answer is C

If the body is in equilibrium then 

F + R = N 

3i - 12j + 7i + 5j = pi + qj

10i - 7j = pi + qj

p = 10, q = -7

145.

Find the angle between i + 5j and 5i - J

A.

0\(^o\)

B.

45\(^o\)

C.

60\(^o\)

D.

90\(^o\)

Correct answer is D

a = i + 5j and b = 5i - j

cos\(\theta\) = \(\frac{a.b}{|a|.|b|}\)

= \(\frac{(1 \times 5) + (5x - 1)}{(\sqrt{1^2 + 5^2}) (5^2 + (-1))^2}\)

= \(\frac{5 - 5}{\sqrt{26}\times \sqrt{26}}\) = 0

x = cos\(^{-1}\)(0), x = 90\(^o\)