Question 81:

• WAEC 2016

A body of mass 10kg moving with a velocity of 5\(ms^{-1}\) collides with another body of mass 15kg moving in the same direction as the first with a velocity of 2\(ms^{-1}\). After collision, the two bodies move together with a common velocity v\(ms^{-1}\).

A. 3.2
B. 5.3
C. 7.0
D. 8.0

Question 82:

• WAEC 2016

Find the unit vector in the direction of \(-2i + 5j\).

A. \(\frac{1}{\sqrt{29}}(2i + 5j)\)
B. \(\frac{1}{\sqrt{29}}(-2i + 5j)\)
C. \(\frac{1}{29}(2i - 5j)\)
D. \(\frac{1}{29}(-2i - 5j)\)

Question 83:

• WAEC 2016

Given that \(n = 10\) and \(\sum d^{2} = 20\), calculate the Spearman's rank correlation coefficient.

A. 0.121
B. 0.733
C. 0.879
D. 0.979

Question 84:

• WAEC 2016

Find the variance of 11, 12, 13, 14 and 15.

A. 2
B. 3
C. \(\sqrt{2}\)
D. 13

Question 85:

• WAEC 2016

A fair coin is tossed 3 times. Find the probability of obtaining exactly 2 heads.

A. \(\frac{1}{8}\)
B. \(\frac{3}{8}\)
C. \(\frac{5}{8}\)
D. \(\frac{7}{8}\)