Question 6:

• WAEC 2018

The marks scored by 4 students in Mathematics and Physics are ranked as shown in the table below

Mathematics	3	4	2	1
Physics	4	3	1	2

Calculate the Spearmann's rank correlation coefficient.

A. 0.2
B. 0.5
C. 0.6
D. 0.7

Question 7:

• WAEC 2018

Given that \(a = i - 3j\) and \(b = -2i + 5j\) and \(c = 3i - j\), calculate \(|a - b + c|\).

A. \(\sqrt{13}\)
B. \(3\sqrt{13}\)
C. \(6\sqrt{13}\)
D. \(9\sqrt{13}\)

Question 8:

• WAEC 2018

What is the probability of obtaining a head and a six when a fair coin and and a die are tossed together?

A. \(\frac{1}{12}\)
B. \(\frac{1}{3}\)
C. \(\frac{1}{2}\)
D. \(\frac{2}{3}\)

Question 9:

• WAEC 2018

If \(\overrightarrow{OX} = \begin{pmatrix} -7 \\ 6 \end{pmatrix}\) and \(\overrightarrow{OY} = \begin{pmatrix} 16 \\ -11 \end{pmatrix}\), find \(\overrightarrow{YX}\).

A. \(\begin{pmatrix} 9 \\ -5 \end{pmatrix}\)
B. \(\begin{pmatrix} -23 \\ -5 \end{pmatrix}\)
C. \(\begin{pmatrix} 9 \\ 17 \end{pmatrix}\)
D. \(\begin{pmatrix} -23 \\ 17 \end{pmatrix}\)

Question 10:

• WAEC 2018

A body of mass 28g, initially at rest is acted upon by a force, F Newtons. If it attains a velocity of \(5.4ms^{-1}\) in 18 seconds, find the value of F.

A. 0.0082N
B. 0.0084N
C. 0.082N
D. 0.084N