JAMB Mathematics Past Questions & Answers - Page 66

326.

Approximate 0.9875 to 1 decimal place.

A.

1.1

B.

1.0

C.

0.9

D.

0.10

Correct answer is B

9 is on one decimal place, the next number to it is 8 which will be rounded up to 1 because it is greater than 5 and then added to 9 to give 10, 10 cannot be written, it will then be rounded up to 1 and added to 0. So the answer is 1.0

327.

Calculate the area of an equilateral triangle of side 8cm

A.

8√3

B.

16

C.

4√3

D.

16√3

Correct answer is D

An equilateral triangle has all sides equal and all angles equal as 600

  Area = \(\frac{1}{2}\) absinθ

  Area = \(\frac{1}{2}\) x 8 x 8 x sin60

  = \(\frac{1}{2}\) x 64 x \(\sqrt{\frac{3}{2}}\)

  = 16√3 cm\(^2\)

328.

Which one of the following gives the members of the set A1 n B n C?

A.

Φ

B.

{s}

C.

{t, u}

D.

{y, z}

Correct answer is A

A1 = Elements in the universal set but not in A = {s, w, x, y, z} B = {r, s. t, u} C = {t, u, v, w, x} A1 n B n C = elements common to the three sets = none = empty set = Φ

329.

A box contains two red balls and four blue balls. A ball is drawn at random from the box and then replaced before a second ball is drawn. Find the probability of drawing two red balls.

A.

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

B.

\(\frac{1}{3}\)

C.

\(\frac{1}{4}\)

D.

\(\frac{1}{9}\)

Correct answer is D

Total number of balls = 2 + 4 = 6

  P(of picking a red ball) = \(\frac{2}{6}\) = \(\frac{1}{3}\)

  P(of picking a blue ball) = \(\frac{4}{6}\) = \(\frac{2}{3}\)

  With replacement,

  P( picking two red balls) = \(\frac{1}{3}\) × \(\frac{1}{3}\) = \(\frac{1}{9}\)

330.

if y = 23\(_{five}\) + 101\(_{three}\) find y leaving your answer in base two

A.

1110

B.

10111

C.

11101

D.

111100

Correct answer is B

First we convert the numbers to base ten

  23\(_{five}\)= 2 x 51 + 3 x 50

  = 10 + 3 = 13

  101\(_{five}\) = (1 x 32) + (0 x 31) + (1 x 30)

  = 9 + 0 + 1 = 10

  So, y = 13 + 10 = 23

  To convert 23 to base 2 (as in the diagram above)

Y = 23

  = 10111\(_{five}\)

Answer is B