Question 86:

• WAEC 2016

A box contains 14 white balls and 6 black balls. Find the probability of first drawing a black ball and then a white ball without replacement.

A. 0.21
B. 0.22
C. 0.30
D. 0.70

Question 87:

• WAEC 2016

Given that \(r = 3i + 4j\) and \(t = -5i + 12j\), find the acute angle between them.

A. 14.3°
B. 55.9°
C. 59.5°
D. 75.6°

Question 88:

• WAEC 2016

Find \(\lim\limits_{x \to 3} \frac{2x^{2} + x - 21}{x - 3}\).

A. Zero
B. 1
C. 7
D. 13

Question 89:

• WAEC 2016

Find the gradient to the normal of the curve \(y = x^{3} - x^{2}\) at the point where x = 2.

A. \(\frac{-1}{8}\)
B. \(\frac{1}{8}\)
C. \(\frac{-1}{24}\)
D. \(1\)

Question 90:

• WAEC 2016

Find the minimum value of \(y = 3x^{2} - x - 6\).

A. \(-6\frac{1}{6}\)
B. \(-6\frac{1}{12}\)
C. \(-6\)
D. \(0\)