JAMB Mathematics Past Questions & Answers - Page 397

1,981.

The sum of four numbers is 1214\(_5\). What is the average expressed in base five?

A.

114

B.

141

C.

401

D.

411

Correct answer is B

Convert to base 10, divide and then re-convert to base 5.

1,982.

If \(\frac{9^{2x-1}}{27^{x+1}} = 1\), find the value of x.

A.

8

B.

5

C.

3

D.

2

Correct answer is B

\(\frac{9^{2x - 1}}{27^{x + 1}} = 1\)

\(\implies 9^{2x - 1} = 27^{x + 1}\)

\((3^{2})^{2x - 1} = (3^{3})^{x + 1}\)

\(2(2x - 1) = 3(x + 1) \implies 4x - 2 = 3x + 3\)

\(4x - 3x = 3 + 2 \implies x = 5\)

1,983.

A cinema hall contains a certain number of people. If 22\(\frac{1}{2}\)% are children, 47\(\frac{1}{2}\)% are men and 84 are women, find the number of men in the hall.

A.

63

B.

84

C.

113

D.

133

Correct answer is D

45/2% + 95/2% = 70%
100% - 70% = 30% (i.e women)
=> 30% = 84
1% = 84/30
95/2% = (84/30 x 95/2) = 133.

1,984.

Simplify (√98 -√50)/√32

A.

3

B.

1

C.

1/2

D.

1/4

Correct answer is C

(√98 - √50)/√32 = √(49x2) - √(25x2) √(16x2)
=> (7√2 - 5√2)/4√2 = 1/2

1,985.

Simplify 1 - (7/3 x 5/4) + 3/5

A.

-16/15

B.

-79/60

C.

-37/15

D.

-151/60

Correct answer is B

\(1 - (\frac{7}{3} \times \frac{5}{4}) + \frac{3}{5}\)

= \(1 - \frac{35}{12} + \frac{3}{5}\)

= \(\frac{60 - 175 + 36}{60}\)

= \(\frac{-79}{60}\)