WAEC Further Mathematics Past Questions & Answers - Page 44

216.

The equation of the line of best fit for variables x and y is \(y = 19.33 + 0.42x\), where x is the independent variable. Estimate the value of y when x = 15.

A.

18.91

B.

19.75

C.

25.63

D.

38.23

Correct answer is C

\(y = 19.33 + 0.42x\)

\(\text{The value of y when x = 15} = 19.33 + (0.42 \times 15)\)

= \(19.33 + 6.30\)

= 25.63

217.

In a firing contest, the probabilities that Kojo and Kwame hit the target are \(\frac{2}{5}\) and \(\frac{1}{3}\) respectively. What is the probability that none of them hit the target?

A.

\(\frac{1}{5}\)

B.

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

C.

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

D.

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

Correct answer is B

No explanation has been provided for this answer.

218.

Age(in years) 1 - 5 6 - 10 11 - 15
Frequency 3 5 2

Calculate the standard deviation of the distribution.

A.

1.10

B.

2.36

C.

3.50

D.

7.50

Correct answer is C

Age

(years)

Freq

(f)

Mid-value

(x)

fx \(d = (x - \bar{x})\) \(d^{2}\) \(fd^{2}\)
1 - 5 3 3 9 - 4.5 20.25 60.75
6 - 10 5 8 40 0.5 0.25 1.25
11 - 15 2 13 26 5.5 30.25 60.5
\(\sum =\) 10   75     122.5

\(Mean (\bar {x}) = \frac{\sum fx}{\sum f} = \frac{75}{10} = 7.5\)

\(SD = \sqrt{\frac{\sum fd^{2}}{\sum f}}\)

= \(\sqrt{\frac{122.5}{10}}\)

= \(\sqrt{12.25} = 3.50\)

219.

A particle of mass 2.5 kg is moving at a speed of 12 m/s. If a force of magnitude 10 N acts against it, find how long it takes to come to rest.

A.

1.5 s

B.

3.0 s

C.

4.0 s

D.

6.0 s

Correct answer is B

\(F = ma \)

\(10 = 2.5a \implies a = 4 ms^{-2}\)

Since it is a retarding movement, then \(a = -4 ms^{-2}\).

\(v = u + at; v = 0 ms^{-1}, u = 12 ms^{-1}\)

\(0 = 12 + (-4t) \implies 0 = 12 - 4t\)

\(4t = 12 \implies t = 3 s\)

220.

The area of a sector of a circle is 3\(cm^{2}\). If the sector subtends an angle of 1.5 radians at the centre, calculate the radius of the circle

A.

1 cm

B.

\(\sqrt{2}\) cm

C.

2 cm

D.

4 cm

Correct answer is C

The area of sector in radians = \(\frac{r^{2} \theta}{2}\)

\(3 cm^{2} = \frac{1.5 \times r^{2}}{2}\)

\(r^{2} = \frac{3 \times 2}{1.5} = 4\)

\(r = 2 cm\)