JAMB Mathematics Past Questions & Answers - Page 105

521.

One bag contain 3 blue and 5 red balls, another bag contain 2 blue and 4 red balls respectively. One ball is drawn for each bag. What is the probability both balls are blue

A.

\( \frac{2}{15} \)

B.

\( \frac{3}{24} \)

C.

\( \frac{3}{21} \)

D.

\( \frac{3}{28} \)

Correct answer is B

No explanation has been provided for this answer.

522.

Simplify \( [1 ÷ (x^2 + 3x + 2)] + [1 ÷ (x^2 + 5x + 6)] \)

A.

\( \frac{2}{(x + 1)^2} \)

B.

\( \frac{2}{(x + 1)(x + 2} \)

C.

\( \frac{2}{(x + 1)(x + 2} \)

D.

\( \frac{2}{(x + 1)(x + 3} \)

Correct answer is D

\( [1 ÷ (x^2 + 3x + 2)] + [1 ÷ (x^2 + 5x + 6)] \)

= \( 1 ÷ (x^2 + 3x + 2) + [1 ÷ (x^2 +5x + 6)]\)

= \( [1 ÷ ((x^2 + x) + (2x + 2) )] + [1 ÷ ((x^2 + 3x) + (2x + 6) )] \)

= [1 ÷ (x(x + 2) + 2(x +1))] + [1 ÷ (x(x + 3) +2(x + 3) )]

= [1 ÷ (x + 1)(x + 2)] + [1 ÷ ((x + 3) + (x + 2))]

=((x + 3) + (x + 1)) ÷ (x + 1)(x + 2)(x + 3)

Using the L.C.M

=((x + x + 3 + 1)) ÷ (x + 1)(x + 2)(x + 3)

=(2x+4)/(x+1)(x+2)(x+3) =2(x+2)/(x+1)(x+2)(x+3)

= \( \frac{2 }{(x + 1)(x + 3)} \)

523.

Simplify (0.09)2 and give your answer correct to 4 significant figures

A.

0.81

B.

0.081

C.

0.0081

D.

8.0001

Correct answer is C

(0.09)2 = 0.09 × 0.09

= 0.0081

= 0.008100 to 4 significant figures

Please, start counting first from the non-zero digits i.e. 8

524.

Find the simple interest on N325 in 5years at 3% per annum.

A.

N48.75K

B.

N50.10K

C.

N75.50K

D.

N15.75K

Correct answer is A

I =[ PRT ÷ 100]

[(325 × 5 × 3) ÷ (100)]

N(195 ÷ 4)

N48.75K

525.

If A = (−3,5) and B = (4,−1) find the co-ordinate of the mid point

A.

2, ½

B.

½ , 2

C.

1, ½

D.

0, 2

Correct answer is B

The coordinate of the midpoint is \((\frac{-3 + 4}{2}, \frac{5 + (-1)}{2})\)

= \((\frac{1}{2}, 2)\)