WAEC Further Mathematics Past Questions & Answers - Page 30

146.

Calculate the probability that the product of two numbers selected at random with replacement from the set {-5,-2,4, 8} is positive

A.

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

B.

\(\frac{1}{2}\)

C.

\(\frac{1}{3}\)

D.

\(\frac{1}{6}\)

Correct answer is B

x -5 -2  4 8

-5 25 10 -20 -40

-2 10 4 -8 -16

4 10 4 -8 -16

4 -20 -8 16 32

8 -40 -16 32 64

Pr(Two numbers is positive) = \(\frac{8}{16}\) 

= \(\frac{1}{2}\) 

147.

Find the median of the numbers 9,7, 5, 2, 12,9,9, 2, 10, 10, and 18.

A.

7

B.

9

C.

10

D.

11

Correct answer is B

Rearrange;

2, 2, 5, 7, 9, 9, 9, 10, 10, 11, 12, 18

Median = 9

148.

If X = \(\frac{3}{5}\) and cos y = \(\frac{24}{25}\), where X and Y are acute, find the value of cos (X + Y). 

A.

\(\frac{117}{125}\)

B.

\(\frac{24}{25}\)

C.

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

D.

\(\frac{7}{25}\)

Correct answer is C

Cos (x + y) 

= cos x cos y - sin x sin y

cos (x + y) = \(\frac{4}{5} \times \frac{24}{25} - \frac{3}{5} \times \frac{7}{25}\)

= \(\frac{96}{125} - \frac{21}{125} = \frac{96 - 21}{125}\)

= \(\frac{75}{125}\)

= \(\frac{3}{5}\) 

149.

Given that P = {x : 1 \(\geq\) x \(\geq\) 6} and Q = {x : 2 < x < 10}. Where x are integers, find n(p \(\cap\) Q) 

A.

4

B.

6

C.

8

D.

10

Correct answer is A

P = {1, 2, 3, 4, 5, 6}

Q = {3, 4 , 5, 6, 7, 8, 9}

P \(\cap\) Q = {3, 4, 5, 6}

n(P \(\cup\) Q) = 4

150.

Determine the coefficient of x\(^3\) in the binomial expansion of ( 1 + \(\frac{1}{2}\)x) 

A.

\(\frac{5}{8}\)

B.

\(\frac{5}{6}\)

C.

\(\frac{5}{4}\)

D.

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

Correct answer is C

(1 + \(\frac{1}{2} x )^5\)

1(1)\(^3\)(\(\frac{1}{2} x)^0\) - 5(1)\(^4\)(\(\frac{1}{2} x)^1\)

+ 10 (10)\(^3\)(\(\frac{1}{2} x )^2\) + 10(1)\(^2\) (\(\frac{1}{2} x\))\(^3\) 

Coefficient of x\(^3\) 

10(\(\frac{1}{2} x)^3\) = \(\frac{10}{8} x^3\) =

= \(\frac{5}{4}\)