JAMB Mathematics 2013 past questions and answers

36 questions. Try each one, then open the answer to check yourself and read the explanation.

Question 2

Number Bases

Convert 2710 to another number in base three.

  1. A.11003
  2. B.10003
  3. C.10013
  4. D.10103
Show the answer and explanation

Answer: B (10003)

Explanation

27 = 33, so in base three it is 10003.

Open this question

Question 3

Ratio, Percentages and Rates

3 girls share a number of apples in the ratio 5:3:2. If the highest share is 40 apples, find the smallest share.

  1. A.16
  2. B.38
  3. C.36
  4. D.24
Show the answer and explanation

Answer: A (16)

Explanation

The highest share is 5 parts = 40, so 1 part = 8. The smallest share is 2 parts = 16.

Open this question

Question 4

Fractions, Decimals and Approximation

Evaluate (1.25 × 0.025)/0.05, correct to 1 decimal place.

  1. A.6.3
  2. B.0.5
  3. C.0.6
  4. D.6.2
Show the answer and explanation

Answer: C (0.6)

Explanation

1.25 × 0.025 = 0.03125, and 0.03125 ÷ 0.05 = 0.625, which is 0.6 to 1 decimal place.

Open this question

Question 5

Commercial Arithmetic

Calculate the time taken for N3000 to earn N600 if invested at 8% simple interest.

  1. A.3½ years
  2. B.1½ years
  3. C.2½ years
  4. D.3 years
Show the answer and explanation

Answer: C (2½ years)

Explanation

T = 100I/(PR) = 100 × 600/(3000 × 8) = 2.5 years.

Open this question

Question 6

Indices

Simplify 3−5n/91−n × 27n+1

  1. A.35
  2. B.3
  3. C.32
  4. D.33
Show the answer and explanation

Answer: B (3)

Explanation

In powers of 3: 3−5n ÷ 32 − 2n × 33n + 3 = 3−5n − 2 + 2n + 3n + 3 = 31 = 3.

Open this question

Question 7

Logarithms

If log104 = 0.6021, evaluate log104⅓

  1. A.1.8063
  2. B.0.2007
  3. C.0.3011
  4. D.0.9021
Show the answer and explanation

Answer: B (0.2007)

Explanation

log 4⅓ = ⅓ log 4 = 0.6021 ÷ 3 = 0.2007.

Open this question

Question 8

Surds

Simplify: √5(√147 − √12)/√15

  1. A.1/9
  2. B.9
  3. C.5
  4. D.1/5
Show the answer and explanation

Answer: C (5)

Explanation

√147 = 7√3 and √12 = 2√3, so the top is √5 × 5√3 = 5√15. Dividing by √15 gives 5.

Open this question

Question 9

Sets

P, Q and R are subsets of the universal set U. The venn diagram showing the relationship (P∩Q)∪R is

Diagram for this question
  1. A.Diagram A
  2. B.Diagram B
  3. C.Diagram C
  4. D.Diagram D
Show the answer and explanation

Answer: C (Diagram C)

Explanation

(P ∩ Q) ∪ R is all of circle R together with the overlap of P and Q. Diagram C shades this region.

Open this question

Question 10

Sets

If P = {x: x is odd, −1 < x ≤ 20} and Q = {y: y is prime; −2 < y ≤ 25}, find P∩Q.

  1. A.{3,5,7,11,13,17,19}
  2. B.{2,3,5,7,11,1...}
  3. C.{3,5,7,11,17,19}
  4. D.{...6,11,13,17...}
Show the answer and explanation

Answer: A ({3,5,7,11,13,17,19})

Explanation

P = {1, 3, 5, ..., 19} and Q = {2, 3, 5, 7, 11, 13, 17, 19, 23}. The odd primes up to 19 are in both: {3, 5, 7, 11, 13, 17, 19}.

Open this question

Question 11

Algebraic Expressions

If S = √(t2 − 4t + 4), find t in terms of S.

  1. A.S − 2
  2. B.S2 + 2
  3. C.S2 − 2
  4. D.S + 2
Show the answer and explanation

Answer: D (S + 2)

Explanation

t2 − 4t + 4 = (t − 2)2, so S = t − 2 (taking t ≥ 2) and t = S + 2.

Open this question

Question 12

Polynomials

If x − 4 is a factor of x2 − x − k, then k is

  1. A.20
  2. B.2
  3. C.4
  4. D.12
Show the answer and explanation

Answer: D (12)

Explanation

By the factor theorem, x = 4 gives 16 − 4 − k = 0, so k = 12.

Open this question

Question 13

Polynomials

The remainder when 6p3 − p2 − 47p + 30 is divided by p − 3 is

  1. A.63
  2. B.18
  3. C.21
  4. D.42
Show the answer and explanation

Answer: D (42)

Explanation

Put p = 3: 162 − 9 − 141 + 30 = 42.

Open this question

Question 14

Variation

P varies jointly as m and u, and varies inversely as q. Given that p = 4, m = 3 and u = 2 when q = 1, find the value of p when m = 6, u = 4 and q = 8/5.

  1. A.10
  2. B.288/5
  3. C.128/5
  4. D.15
Show the answer and explanation

Answer: A (10)

Explanation

p = kmu/q: 4 = 6k, so k = 2/3. Then p = (2/3 × 6 × 4) ÷ 8/5 = 16 × 5/8 = 10.

Open this question

Question 15

Variation

If r varies inversely as the square root of s and t, how does s vary with r and t?

  1. A.s varies directly as r2 and t2.
  2. B.s varies directly as r and t.
  3. C.s varies inversely as r and t2.
  4. D.s varies inversely as r2 and t.
Show the answer and explanation

Answer: D (s varies inversely as r2 and t.)

Explanation

r = k/√(st), so r2 = k2/(st) and s = k2/(r2t): s varies inversely as r2 and t.

Open this question

Question 16

Inequalities

Evaluate 3(x + 2) > 6(x + 3)

  1. A.x < −4
  2. B.x > 4
  3. C.x < 4
  4. D.x > −4
Show the answer and explanation

Answer: A (x < −4)

Explanation

3x + 6 > 6x + 18 gives −3x > 12, so x < −4 (the sign flips when dividing by −3).

Open this question

Question 19

Progressions

If the sum of the first two terms of a G.P. is 3 and the sum of the second and the third terms is −6, find the sum of the first term and the common ratio.

  1. A.−5
  2. B.5
  3. C.−2
  4. D.−3
Show the answer and explanation

Answer: A (−5)

Explanation

a(1 + r) = 3 and ar(1 + r) = −6, so r = −2. Then a(−1) = 3 and a = −3. a + r = −5.

Open this question

Question 20

Progressions

The nth term of the progression 4/2, 7/3, 10/4, 13/5, ... is

  1. A.(3n + 1)/(n − 1)
  2. B.(3n + 1)/(n + 1)
  3. C.(1 − 3n)/(n + 1)
  4. D.(3n + 1)/(n + 1)
Show the answer and explanation

Answer: D ((3n + 1)/(n + 1))

Explanation

The numerators 4, 7, 10, 13 are 3n + 1 and the denominators 2, 3, 4, 5 are n + 1, so the nth term is (3n + 1)/(n + 1).

Open this question

Question 21

Binary Operations

If a binary operation * is defined by x * y = x + 2y, find 2*(3*4)

  1. A.14
  2. B.26
  3. C.24
  4. D.16
Show the answer and explanation

Answer: C (24)

Explanation

3 * 4 = 3 + 8 = 11, then 2 * 11 = 2 + 22 = 24.

Open this question

Question 22

Matrices and Determinants

If P = (5 3; 2 1) and Q = (4 2; 3 5), find 2P + Q. (Matrices written row by row.)

  1. A.(7 7; 8 14)
  2. B.(8 14; 7 7)
  3. C.(7 7; 14 8)
  4. D.(14 8; 7 7)
Show the answer and explanation

Answer: D ((14 8; 7 7))

Explanation

2P = (10 6; 4 2). Adding Q: (14 8; 7 7).

Open this question

Question 23

Matrices and Determinants

Find the inverse of (5 3; 6 4). (Matrices written row by row.)

  1. A.(2 3/2; −3 −5/2)
  2. B.(2 3/2; −3 5/2)
  3. C.(2 −3/2; −3 −5/2)
  4. D.(2 −3/2; −3 5/2)
Show the answer and explanation

Answer: D ((2 −3/2; −3 5/2))

Explanation

The determinant is 20 − 18 = 2. Swap the diagonal and change the other signs, then halve: ½(4 −3; −6 5) = (2 −3/2; −3 5/2).

Open this question

Question 24

Triangles and Quadrilaterals

In the diagram above, find the value of x.

Diagram for this question
  1. A.45°
  2. B.15°
  3. C.30°
  4. D.40°
Show the answer and explanation

Answer: D (40°)

Explanation

The marked equal sides make the small triangle isosceles, so both its base angles are 15° and its exterior angle is 30°. In the big triangle, x = 180° − 110° − 30° = 40°.

Open this question

Question 28

Circle Theorems

Find the length of a chord which subtends an angle of 90° at the centre of a circle whose radius is 8cm.

  1. A.8√3 cm
  2. B.4 cm
  3. C.8 cm
  4. D.8√2 cm
Show the answer and explanation

Answer: D (8√2 cm)

Explanation

The two radii and the chord form a right-angled triangle, so chord = √(82 + 82) = 8√2 cm.

Open this question

Question 30

Loci

The locus of the points which is equidistant from the line PQ forms a

  1. A.perpendicular line to PQ
  2. B.circle centre P
  3. C.circle centre Q
  4. D.pair of parallel lines to PQ.
Show the answer and explanation

Answer: D (pair of parallel lines to PQ.)

Explanation

All points a fixed distance from a straight line lie on two lines parallel to it, one on each side. So the locus is a pair of parallel lines to PQ.

Open this question

Question 31

Coordinate Geometry

If the mid point of the line PQ is (2,3) and the point P is (−2,1), find the coordinate of the point Q.

  1. A.(8,6)
  2. B.(5,6)
  3. C.(0,4)
  4. D.(6,5)
Show the answer and explanation

Answer: D ((6,5))

Explanation

Q = (2 × 2 − (−2), 2 × 3 − 1) = (6, 5).

Open this question

Question 32

Coordinate Geometry

Find the equation of the perpendicular bisector of the line joining P(2, −3) to Q(−5, 1)

  1. A.8y + 14x + 13 = 0
  2. B.8y − 14x + 13 = 0
  3. C.8y − 14x − 13 = 0
  4. D.8y + 14x − 13 = 0
Show the answer and explanation

Answer: C (8y − 14x − 13 = 0)

Explanation

The midpoint is (−3/2, −1) and PQ has gradient −4/7, so the bisector has gradient 7/4: y + 1 = 7/4 (x + 3/2). Multiplying by 8 gives 8y − 14x − 13 = 0.

Open this question

Question 33

Trigonometry

In triangle PQR, q = 8 cm, r = 6cm and Cos P = 1/12. Calculate the value of p.

  1. A.√108 cm
  2. B.9cm
  3. C.√92 cm
  4. D.10 cm
Show the answer and explanation

Answer: C (√92 cm)

Explanation

Cosine rule: p2 = 64 + 36 − 2 × 8 × 6 × 1/12 = 100 − 8 = 92, so p = √92 cm.

Open this question

Question 34

Trigonometry

If tan θ = 3/4, find the value of sin θ + cos θ.

  1. A.1⅓
  2. B.1⅔
  3. C.1⅗
  4. D.1⅖
Show the answer and explanation

Answer: D (1⅖)

Explanation

A 3-4-5 triangle gives sin θ = 3/5 and cos θ = 4/5, so the sum is 7/5 = 1⅖.

Open this question

Question 37

Differentiation

The radius of a circle is increasing at the rate of 0.02 cms−1. Find the rate at which the area is increasing when the radius of the circle is 7 cm.

  1. A.0.35cm2s−1
  2. B.0.88cm2s−1
  3. C.0.75cm2s−1
  4. D.0.55cm2s−1
Show the answer and explanation

Answer: B (0.88cm2s−1)

Explanation

dA/dt = 2πr × dr/dt = 2 × 22/7 × 7 × 0.02 = 0.88 cm2/s.

Open this question

Question 38

Integration

Integrate ((1 + x)/x3) dx.

  1. A.2x2 − 1/x + k
  2. B.−1/(2x2) − 1/x + k
  3. C.−x2/2 − 1/x + k
  4. D.x2 − 1/x + k
Show the answer and explanation

Answer: B (−1/(2x2) − 1/x + k)

Explanation

Split as x−3 + x−2. Integrating gives −x−2/2 − x−1 + k = −1/(2x2) − 1/x + k.

Open this question

Question 42

Measures of Central Tendency

Find the mean of t + 2, 2t − 4, 3t + 2 and 2t.

  1. A.2t + 1
  2. B.t
  3. C.t + 1
  4. D.2t
Show the answer and explanation

Answer: D (2t)

Explanation

The sum is 8t and there are 4 terms, so the mean is 2t.

Open this question

Question 43

Measures of Central Tendency

The mean of seven numbers is 10. If six of the numbers are 2, 4, 8, 14, 16 and 18, find the mode.

  1. A.14
  2. B.2
  3. C.6
  4. D.8
Show the answer and explanation

Answer: D (8)

Explanation

The seven numbers total 70 and the six given add to 62, so the seventh is 8. Then 8 appears twice, making it the mode.

Open this question

Question 45

Measures of Dispersion

If the variance of 3 + x, 6, 4, x, and 7 − x is 4 and the mean is 5, find the standard deviation.

  1. A.3
  2. B.√2
  3. C.√3
  4. D.2
Show the answer and explanation

Answer: D (2)

Explanation

The standard deviation is the square root of the variance: √4 = 2.

Open this question

Question 46

Measures of Dispersion

Score: 3, 4, 5, 6, 7, 8, 9, 10
Frequency: 1, 0, 7, 5, 2, 3, 1, 1
The table above shows the scores of 20 students in Further Mathematics test. What is the range of the distribution?

  1. A.3
  2. B.10
  3. C.7
  4. D.6
Show the answer and explanation

Answer: C (7)

Explanation

Range = highest score − lowest score = 10 − 3 = 7.

Open this question

Question 47

Permutation and Combination

In how many ways can a student select 2 subjects from 5 subjects?

  1. A.5!/(2!3!)
  2. B.5!/2!
  3. C.5!/3!
  4. D.5!/(2!2!)
Show the answer and explanation

Answer: A (5!/(2!3!))

Explanation

Choosing 2 from 5 when order does not matter is 5C2 = 5!/(2! 3!).

Open this question

Question 48

Permutation and Combination

In how many ways can three seats be occupied if 5 people are willing to sit?

  1. A.5
  2. B.120
  3. C.60
  4. D.20
Show the answer and explanation

Answer: C (60)

Explanation

Order matters on the seats: 5P3 = 5 × 4 × 3 = 60.

Open this question

Question 50

Probability

A basket contains 9 apples, 8 bananas and 7 oranges. A fruit is picked from the basket, find the probability that it is neither an apple nor orange.

  1. A.7/24
  2. B.2/3
  3. C.3/8
  4. D.1/3
Show the answer and explanation

Answer: D (1/3)

Explanation

"Neither an apple nor an orange" means a banana: 8 out of 24 fruits, so 8/24 = 1/3.

Open this question