WAEC Further Mathematics Past Questions & Answers - Page 37

181.

Calculate the mean deviation of 5, 8, 2, 9 and 6

A.

5

B.

4

C.

3

D.

2

Correct answer is D

x x - \(\bar{x}\) (x - \(\bar{x}\))

5

8

2

9

6

-1

2

-4

3

0

1

2

4

3

0

 

\(\bar{x}\) = \(\frac{30}{5}\) = 6

\(\sum |x - \bar{x}|\)

= 10

Mean deviation = \(\frac{10}{5}\)

= 2

182.

If the mean of 2, 5, (x + 1), (x + 2), 7 and 9 is 6, find the median.

A.

6.5

B.

6.0

C.

5.5

D.

5.0

Correct answer is C

\(\frac{1 + 5 + x + 6 + x + 2 + 7 + 9}{6}\) = 6

26 + 2x = 36 

2x = 36 - 26

2x = 10 

x = \(\frac{10}{2}\) = 5

2, 5, 6, 7, 7, 9

Median = \(\frac{6 + 7}{2}\) = 6.5 

183.

Find the coordinates of the point in the curve y = 3x\(^2\) - 2x - 5 where the tangent is parallel to the line y = - 5 = 8x

A.

\(\begin{pmatrix} - \frac{5}{3} &, 0 \end {pmatrix}\)

B.

\(\begin{pmatrix} 0, & - \frac{5}{3} \end {pmatrix}\)

C.

\(\begin{pmatrix} 0, & \frac{5}{3} \end {pmatrix}\)

D.

\(\begin{pmatrix} \frac{5}{3} &, 0 \end {pmatrix}\)

Correct answer is D

y = 8x + 5 

m = 8

y = 3x\(^2\) - 2x - 5 

\(\frac{dy}{dx}\) = 6x - 2x - 5

\(\frac{6x}{6} = \frac{10}{6}\) 

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

y = 0 

185.

The second and fourth terms of an exponential sequence (G.P) are \(\frac{2}{9}\) and \(\frac{8}{81}\) respectively. Find the sixth term of the sequence 

A.

\(\frac{81}{32}\)

B.

\(\frac{9}{8}\)

C.

\(\frac{1}{4}\)

D.

\(\frac{32}{729}\)

Correct answer is D

ar = \(\frac{2}{9}\) .....(i) 

ar\(^3\) = \(\frac{8}{81}\) ......(ii) 

\(\frac{ar3}{ar} = \frac{8}{81} \times \frac{9}{2}\) 

r\(^2 = \frac{4}{9}\) 

r = \(\sqrt{\frac{4}{9}}\) 

= \(\frac{2}{3}\) 

ar = \(\frac{2}{9}\) 

a(\(\frac{2}{3}\)) = \(\frac{2}{9}\)

a = (\(\frac{2}{3}\)) = \(\frac{2}{9}\)

a = \(\frac{2}{9} \times \frac{3}{2}\)

a = \(\frac{1}{3}\) 

T\(_r\) = ar\(^5\) = (\(\frac{1}{3}\))(\(\frac{2}{5}\))\(^5\) 

= \(\frac{32}{729}\)