JAMB Mathematics Past Questions & Answers - Page 62

306.

Simplify: \(\sqrt{108} + \sqrt{125} - \sqrt{75}\)

A.

\(\sqrt{3} + 5\sqrt{5}\)

B.

\(6 \sqrt{3} - 5 \sqrt{5}\)

C.

\(6 \sqrt{3} + \sqrt{2}\)

D.

\(6\sqrt{3} - \sqrt{2}\)

Correct answer is A

\(\sqrt{108} + \sqrt{125} - \sqrt{75}\)

= \(\sqrt{3 \times 36} + \sqrt{5 \times 25} - \sqrt{3 \times 25}\)

= \(6 \sqrt{3} + 5 \sqrt{5} - 5 \sqrt{3}\)

= \(\sqrt{3} + 5\sqrt{5}\)

307.

Add 54 \(_{eight}\) and 67\(_{eight}\) giving your answers in base eight

A.

111

B.

121

C.

123

D.

143

Correct answer is D

54 \(_{eight}\) and 67\(_{eight}\) = 1438

  Starting with normal addition, 4 + 7 gives 11

  (it is more than the base, 8) 8 goes in 11 just 1 time, remaining 3, the remainder will be written, and the 1 will be added to the sum of 5 and 6 which gives 12 altogether, 8 goes in 12 one time remaining 4, the remainder 4 was written and then the 1 that was the quotient was then written since nothing to add the 1 to.

  So answer is 143 in base eight

308.

From a point R, 300m north of P, a man walks eastwards to a place; Q which is 600m from P. Find the bearing of P from Q correct to the nearest degree

A.

026\(^o\)

B.

045\(^o\)

C.

210\(^o\)

D.

240\(^o\)

Correct answer is D

Cos θ = \(\frac{adj}{hyp}\)

  = \(\frac{300}{600}\)

  = 0.5

  θ = Cos - 10.5

  = 60

  ∠ RPQ = ∠ PQs

  So the bearing of P from Q is 180 + 60 = 240\(^o\)

  Answer is D

309.

Simplify 25\(\frac{1}{2}\) × 8\(\frac{-2}{3}\)

A.

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

B.

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

C.

6

D.

10

Correct answer is A

Using law of indices

25\(\frac{1}{2}\) × 8\(\frac{-2}{3}\)

  = √25 x (\(\sqrt[3]{8}\)) -2

  = 5 x 2-2

  = 5 x \(\frac{1}{2^2}\) =

 \(\frac{5}{4}\) = \(\frac{11}{4}\)

  Answer is A

310.

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