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JAMB Mathematics Past Questions & Answers - Page 99

491.

The volume of a cylinder whose height is 4cm and whose radius 5cm is equal to (π = 3.14)

A.

3.13cm2

B.

145cm2

C.

314cm2

D.

214cm2

Correct answer is C

“Explanation

V = πr2h

V = ?, h = 4cm, r = 5cm

V = 3.14(5)2 (4)

V = 3.14(25)(4)

V = 3.14 × 1200

= 314cm2

492.

Solve x2 − 2x − 3 = 0

A.

x = 2 or 1

B.

x = 3 or -1

C.

x = 1 or 0

D.

x = 1 or 2

Correct answer is B

x2 − 2x − 3 = 0

−3x + x = − 2x

− 3x × x = − 3x2

(x2 − 3x)(x − 3) = 0

(x − 3)(x + 1) = 0

Either (x − 3) = 0 or (x + 1) = 0

x = 3 or − 1

493.

Find the value of x if [1÷64(x+2)]=[4(x3)÷16x]

A.

32

B.

23

C.

13

D.

32

Correct answer is D

[1÷64(x+2)]=[4(x3)÷16x]

64(x+2)=[4(x3)]÷[16x]

breakdown 4,16,64 into a small index no

26(x+2)=22(x3)÷24(x)

26x12=22x4x6

26x12=22x6

− 6x − 12 = − 2x − 6

Collect the like term

−6x + 2x = −6 + 12

−4x =6

x = 64

x = 32

494.

A man sells his new brand car for N420,000 at a gain of 15%. What did it cost him?

A.

N410,000

B.

N365, 217

C.

N157, 250

D.

N257,000

Correct answer is B

Cost Price:

Selling price = 100 : (100 + 15)

= 100 : 115

Cost Price

= 100 ÷ 115 of selling price (i.e N420,000)

= 100 ÷ 115 × N420,000

= N365,217.4

∴ Cost Price = N365, 217

495.

Find x if 132x = 70 eight.

A.

5

B.

3

C.

6

D.

1

Correct answer is C

132x = 708

1×x2+3×x1+2×x0

7×81+0×80

x2+3x+256=0

x2+3x54=0

x(x + 9)−6(x + 9) = 0

(x + 9)(x − 6) = 0

Either (x + 9) = 0 or (x − 6) = 0

x = − 9 or +6

The positive values for x = 6

The base number for 132x = 1326