JAMB Mathematics Past Questions 2015

10 questions from the JAMB 2015 Mathematics paper, with answers and explanations. Tap "Show answer" under each one when you are ready.

JAMB 2015Question 1 · Algebraic Processes

Factorize

x^{2} + 9 x + 20

A.(x − 5) 2
B.(x + 5)(x + 4)
C.(x – 5)(x + 3)
D.(x + 3) 2

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Answer: B. (x + 5)(x + 4)

x²+9x+20=(x+5)(x+4).

JAMB 2015Question 2 · Algebraic Processes

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

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Answer: D. $\frac{2}{( x + 1 ) ( x + 3}$

Combining fractions gives 2/[(x+1)(x+3)].

JAMB 2015Question 3 · Commercial Arithmetic

In a town of 6250 inhabitants, there were 62 births during 1984. Find the percentage birth rate

A.3%
B.1.0%
C.2.5%
D.5.40%

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Answer: B. 1.0%

$\frac{62}{6250}$ ×100 ≈ 1.0%.

JAMB 2015Question 4 · Commercial Arithmetic

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

A.N48.75K
B.N50.10K
C.N75.50K
D.N15.75K

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Answer: A. N48.75K

SI=325×3× $\frac{5}{100}$ =48.75.

JAMB 2015Question 5 · Coordinate Geometry and Trigonometry

If x + y = 90 simplify

(s in x + s in y)^{2}

−2sinxsiny

A.1
B.0
C.2
D.-1

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Answer: A. 1

With y=90-x, siny=cosx, so expression = sin²x+cos²x = 1.

JAMB 2015Question 6 · Geometry and Mensuration

Find the area of the curved surface of a cone whose base radius is

3 cm

and whose height is

4 cm

(π = 3.14)

A. $17.1 c m^{2}$
B. $27.2 c m^{2}$
C. $47.1 c m^{2}$
D. $37.3 c m^{2}$

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Answer: C. $47.1 c m^{2}$

Slant height=5; CSA=πrl=3.14×3×5=47.1.

JAMB 2015Question 7 · Number, Fractions, and Approximation

Simplify 1¼ ÷ (2 ÷ ¼ of 28)

A.1 $\frac{3}{8}$
B.2 $\frac{3}{4}$
C.4 $\frac{3}{8}$
D.3 $\frac{1}{5}$

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Answer: C. 4 $\frac{3}{8}$

¼ of 28=7; 2÷7= $\frac{2}{7}$ ; 1¼÷( $\frac{2}{7}$ )= $\frac{35}{8}$ =4⅜.

JAMB 2015Question 8 · Number, Fractions, and Approximation

Find the value of x if [ 1 ÷

6 4^{(x + 2)}

]= [

4^{(x - 3)}

1 6^{x}

]

A. $\frac{3}{2}$
B. $\frac{2}{3}$
C. $\frac{1}{3}$
D.- $\frac{3}{2}$

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Answer: D. - $\frac{3}{2}$

Equating powers of 4 gives -3(x+2)=-x-3, so x=-3/2.

JAMB 2015Question 9 · Number, Fractions, and Approximation

Evaluate

lo g_{5} (\frac{y ^{2} x ^{5}}{125 b ^{\frac{1}{2}}})

A. $2 lo g_{5} y + 5 lo g_{5} y^{2} - 3$
B. $lo g_{5} y^{2} + 5 lo g_{5} x + 3$
C. $25 lo g_{y} 5 + 3$
D. $2 lo g_{5} y + 5 lo g_{5} x - \frac{1}{2} lo g_{5} b - 3$

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Answer: D. $2 lo g_{5} y + 5 lo g_{5} x - \frac{1}{2} lo g_{5} b - 3$

$lo g_{5} (\frac{y ^{2} x ^{5}}{125 b ^{1/2}}) = 2 lo g_{5} y + 5 lo g_{5} x - 3 - \frac{1}{2} lo g_{5} b$ .

JAMB 2015Question 10 · Sequences, Series, and Variation

If an investor invest N450,000 in a certain organization in order to yield X as a return of N25,000. Find the return on an investment of N700,000 by Y in the same organization.

A.N14,950.50K
B.N25,150.30K
C.N15,000.00K
D.N38,888.90K

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Answer: D. N38,888.90K

Rate= $\frac{25000}{450000}$ ; return on 700,000 ≈ 38,888.90.

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JAMB Mathematics Past Questions 2015

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