JAMB Mathematics Past Questions & Answers - Page 177

881.

Simplify \(\frac{\sqrt{2}}{\sqrt{3} - \sqrt{2}}\) - \(\frac{3 - 2}{\sqrt{3} + \sqrt{2}}\)

A.

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

B.

3(\(\sqrt{6}\) - 1)

C.

\(\sqrt{6}\) - 3

D.

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

E.

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

Correct answer is B

\(\frac{\sqrt{2}}{\sqrt{3} - \sqrt{2}}\) - \(\frac{3 - 2}{\sqrt{3} + \sqrt{2}}\)

\(\frac{\sqrt{2}}{\sqrt{3} - \sqrt{2}}\) = \(\frac{\sqrt{2}}{\sqrt{3}}\) - \(\frac{x}{\sqrt{2}}\)

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

\(\frac{\sqrt{3} - \sqrt{2}}{\sqrt{3} + \sqrt{2}}\) = \(\frac{\sqrt{3} - \sqrt{2}}{\sqrt{3} + \sqrt{2}}\) x \(\frac{\sqrt{3} - \sqrt{2}}{\sqrt{3} - \sqrt{2}}\)

= 5 - 2\(\sqrt{6}\)

\(\sqrt{6}\) + 2 - (5 - 2 \(\sqrt{6}\)) = \(\sqrt{6}\) + 2 - 5 + 2\(\sqrt{6}\)

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

= 3(\(\sqrt{6}\) - 1)

882.

In one and a half hours, the minute hand of a clock rotates through an angle of

A.

90o

B.

180o

C.

640o

D.

450o

E.

540o

Correct answer is E

1 hr = 60 mins, 60 mins = 360°

30 mins = \(\frac{360^o}{1}\) × \(\frac{30}{60}\)

= 180°

90 mins = 360° + 180°

= 540°

883.

A micrometer is defined as one millionth of a millimeter. A length of 12,000 micrometres may be represented as

A.

0.00012m

B.

0.0000012m

C.

0.000012m

D.

0.00000012m

E.

0.000000012m

Correct answer is C

1 UM = 10-6mm = 10-9m
1.2 x 104 x 10-9m = 1.2 x 10-5m (0.000012)

884.

An isosceles triangle of sides 13cm, 13cm, 10cm is inscribed in a circle. What is the radius of the circle?

A.

7cm

B.

12cm

C.

8cm

D.

36cm

E.

69cm

Correct answer is A

In \(\Delta DAC, \stackrel\frown{DAC} = \theta\)

\(\sin \theta = \frac{5}{13}\)

\(\theta = 22.6°\)

\(< DOC = 22.6° \times 2 = 45.2°\)

\(\sin 45.2 = \frac{5}{r} \implies r = \frac{5}{\sin 45.2}\)

\(r = 7.046cm\)

= \(7\frac{1}{24} cm\)

885.

By selling an article for N45.00 a man makes a profit of 8%. For how much should he have sold it in order to make a profit of 32%?

A.

N180.00

B.

N59.00

C.

N63.00

D.

N58.00

E.

N55.00

Correct answer is E

When C.P = N45.00 at 8% profit

C.P = \(\frac{100}{108}\) x 45

at profit of 32%, S.P = \(\frac{132}{100}\) x c.p

= \(\frac{132}{100}\) x \(\frac{100 \times 45}{108}\)

= \(\frac{5940}{108}\)

= N55.00