JAMB Mathematics Past Questions & Answers - Page 98

486.

Rationalize 5 ÷ (2 − √3)

A.

3(2 + √5)

B.

2(3 + √5)

C.

5(2 + √3)

D.

3 √2 + 1

Correct answer is C

5÷ (2 − √3)

Using conjugate surds

[5 ÷ (2 − √3)]×(2 + √3) ÷ (2 + √3)]

[5(2+√3)÷((2− √3))2]

[5(2 +√3) ÷ (2)2− (√3)2]

[5(2 +√3) ÷(4− 3)]

= 5(2 + √3)

487.

A public car dealer marked up the cost of a car at 30% in an attempt to make 20% gross profit. Due to the value of dollar, he now placed 20% discount on the car. What profit or loss will he make?

A.

3%

B.

2%

C.

4%

D.

1%

Correct answer is C

Let assume the cost price is 100%

Marked up price + cost price = 20 + 100 = 120%

Discount at 20% = 20/100 × 120 % of cost price

Selling price = cost price − gain

= (120 − 24)% of cost price

= 96% of cost price

Loss = (100− 96)% of cost price

= 4% of cost price

∴ He will wake 4% loss

488.

Simplify 2.04 × 3.7 (Leave your answer in 2 decimal place)

A.

7.51

B.

7.71

C.

5.5

D.

7.55

Correct answer is D

2.04 x 3.7
=
204
x 37
-----
7548 = 7.548

= 7.55(2dp)

489.

If duty is levied at 25%, find the duty to be added to a bill of N80.

A.

N100

B.

N20

C.

N80

D.

N150

Correct answer is B

25% of N80 = 25/100 × 80

= N20.00

490.

How many sides has a regular polygon whose interior angles are 120°each

A.

4

B.

5

C.

6

D.

3

Correct answer is C

Each exterior angle = 180 − 120=60

Exterior angle =360/n

60 = 360/n

n =360/6

= 6