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JAMB Mathematics Past Questions & Answers - Page 200

996.

If cos θ = 32 and θ is less than 90o. Calculate cot(90θ)sin2θ

A.

43

B.

43

C.

32

D.

13

E.

23

Correct answer is A

cot(90θ)sin2θ

cot(90θ)=tanθ

\tan \theta = \frac{\sqrt{3}}{3}

\sin \theta = \frac{1}{2} \implies \sin^{2} \theta = \frac{1}{4}

\frac{\cot(90 - \theta)}{\sin^{2} \theta} = \frac{\sqrt{3}}{3}\div\frac{1}{4}

= \frac{4}{\sqrt{3}}

997.

Find the area of a regular hexagon inscribed in a circle of radius 8cm

A.

16\sqrt{3} cm3

B.

96\sqrt{3} cm3

C.

192\sqrt{3} cm3

D.

16\sqrt{3} cm2

E.

33cm2

Correct answer is B

Area of a regular hexagon = 8 x 8 x sin 60o

= 32 x \frac{\sqrt{3}}{2} 

Area = 16\sqrt{3} x 6 = 96 \sqrt{3}cm2

998.

What is the probability that a number chosen at random from the intergers between 1 and 10 inclusive is either a prime or a multiple of 3?

A.

\frac{7}{10}

B.

\frac{3}{5}

C.

\frac{4}{5}

D.

\frac{3}{10}

Correct answer is B

Simple Space: (1, 2, 3, 4, 5, 6, 7, 8, 9, 10 = 10)

Prime: (2, 3, 5, 7)

multiples of 3: (3, 6, 9)

Prime or multiples of 3: (2, 3, 5, 6, 7, 9 = 6)

Probability = \frac{6}{10}

= \frac{3}{5}

999.

Without using table, calculate the value of 1 + sec2 30o

A.

2\frac{1}{3}

B.

\frac{2}{15}

C.

\frac{5}{3}

D.

3\frac{1}{2}

Correct answer is A

1 + sec2 30o = sec 30o

= \frac{2}{\sqrt{3}}

\frac{(2)^2}{3}

= \frac{4}{3}

1 + sec2 30o = sec 30o

= 1 + \frac{4}{3}

= 2\frac{1}{3}

1000.

The bearing of a bird on a tree from a hunter on the ground is N72oE. What is the bearing of the hunter from the birds?

A.

S 18o W

B.

S 72o W

C.

S 72o E

D.

S 27o E

E.

S 27o W

Correct answer is B

B = Bird ; H = Hunter.

Bearing of the hunter from the bird = S 72° W.