Mathematics 2020 Past Questions | JAMB
Study the following Mathematics past questions and answers for JAMB, WAEC NECO and Post-JAMB. Get prepared with official past questions and answers for upcoming examinations.
- Evaluate (212)_{3}– (121)_{3}+ (222)_{3}
- A. (313)_{3}
- B. (1000)_{3}
- C. (1020)_{3}
- D. (1222)_{3}
Correct Option: Answer is C
Solution:
(212)3
(121)3
21
121
——————
(1020)3
2. Factorise (4a + 3)^{2}– (3a – 2)^{2}
- A. (a + 1)(a + 5)
- B. (a – 5)(7a – 1)
- C. (a + 5)(7a + 1)
- D. a(7a + 1)
Correct Option: Answer is C
Solution:
[(4a + 3)^{2} – (3a – 2)2 = a^{2} – b^{2} = (a + b) (a – b)
= [(4a + 3) + (3a – 2)] [(4a + 3) + (3a – 2)]
= [4a + 3 + 3a – 2] [4a + 3 – 3a + 2]
= (7a + 1)(a + 5)
(a + 5) (7a + 1)
3. Find all median of the numbers 89, 141, 130, 161, 120, 131, 131, 100, 108 and 119
- A. 131
- B. 125
- C. 123
- D. 120
Correct Option: Answer is B
Solution:
Arrange in ascending order
89, 100, 108, 119, 120,130, 131, 131, 141, 161
Median = 120+130/2 = 125
4. Find all real number x which satisfy the inequality 1/3(x + 1) – 1 > 1/5(x + 4)
- A. x < 11
- B. x < -1
- C. x > 6
- D. x > 11
Correct Option: Answer is D
Solution:
1/3(x + 1) – 1 > 1/5(x + 4) = x+1/3 – 1 > x+4/5;
x+1/3 – x+4/5 – >0; 5x+5-3x-12/15
2x-7>15; 2x > 22
x >11
5. Reach each number to two significant figures and then evaluate 0.02174 x 1.2047/ 0.023789
- A. 0
- B. 0.9
- C. 1.1
- D. 1.2
Correct Option: Answer is B
Solution:
0.02174 x 1.2047/ 0.023789 to 2 s.f
= 0.0255 x 1.2/ 0.024
= 0.0264/0.024 = 1.1
6. Four boys and ten girls can cut a field first in 5 hours. If the boys work at 5/4the rate at which the girls work, how many boys will be needed to cut the field in 3 hours?
- A. 180
- B. 60
- C. 25
- D. 20
Correct Option: Answer is D
Solution:
Let x rep. numbers of boys that can work at 54 the rate at
which the 10 girls work
For 1 hrs, x boys will work for 15×104
x = 54 x 10
= 8 boys
8 boys will do the work of ten girls at the same rate
4 + 8 = 12 bous cut the field in 5 hrs for 3 hrs,
12×53 boys will be needed = 20 boys.
7. What is the circumference of latitude 0^{o}S if R is the radius of the earth?
- A. cosθ
- B. 2πR cosθ
- C. R sin θ
- D. 2 πr sinθ
Correct Option: Answer is B
Solution:
Circumstances of latitude 0^{o}s where R is the radius of the earth 2πr cos θ
8. A room is 12m long, 9m wide and 8m high. Find the cosine of the angle which a diagonal of the room makes with the floor of the room
- A. 15/17
- B. 8/17
- C. 8/15
- D. 12/17
Correct Option: Answer is C
Solution:
ABCD is the floor. By Pythagoras
AC2 = 144 + 81 = √225
AC = 15cm
Height of room 8m, diagonal of floor is 15m
Therefore, the cosine of the angle which a diagonal of the room makes with the floor is
EC^{2} = 15^{2} + 8^{2} cosine
Adj/Hyp = 15/17
EC^{2} = √225+64
EC = √289
= 17
Adj/Hyp=15/17
9. The goals scored by 40 football teams from three league divisions are recorded below
No of goals | 0 | 1 | 2 | 3 | 4 | 5 | 6 |
Frequency | 4 | 3 | 15 | 16 | 1 | 0 | 1 |
What is the total number of goals scored by all the teams?
- A. 21
- B. 40
- C. 91
- D. 96
Correct Option: Answer is C
Solution:
10. In a class of 150 students, the sector in a pie chart representing the students offering physics has angle 12^{o}. How many students are offering physics?
- A. 18
- B. 15
- C. 10
- D. 5
Correct Option: Answer is D
No of students offering physics are
12/360 x 150 = 5
11. If log10^{2} = 0.3010 and log10^{3} = 0.4771, eventually without using the logarithm tables, log10^{5}
- A. 0.3010
- B. 0.4771
- C. 0.6532
- D. 0.9542
Correct Option: Answer is C
12.
Simplify \(\frac{324 – 4x^2}{2x + 18}\)
- A. 2(x – 9)
- B. 2(9 + x)
- C. 81 – x22
- D. -2(x – 9)
Correct Option: Answer is D
324 – 4x\(^2\) = 18\(^2\) – (2x)\(^2\) = (18 – 2x)(18 + 2x)
2x + 18 = 2x + 18 = (2x + 18)
18 – 2x = 2(a – x) or -2(x – a)
13. In preparing rice cutlets, a cook used 75g of rice, 40g of margarine, 105g of meat and 20g of bread crumbs. Find the angle of the sector which represent meat in a pie chart?
- A. 30^{o}
- B. 60^{o}
- C. 112.5^{o}
- D. 157.5^{o}
Correct Option: Answer is A
Rice = 75g, Margarine = 40g, Meat = 105g
Bread = 20g
Total = 240
Angle of sector represented by meat = 105/240×360/1 = 157.5
14. The angle of a sector of a circle radius 10.5 cm is 48^{o}. Calculate the perimeter of the sector.
- A. 25.4cm
- B. 25.4cm
- C. 25.6cm
- D. 29.8cm
Correct Option: Answer is D
The lenght of Arc AB = \(\frac{Q}{360}\) 2\(\pi\)r
= \(\frac{48}{360}\) x 2\(\frac{22}{7}\) x 10.5 = \(\frac{48}{360}\) x 2\(\frac{22}{7}\) x \(\frac{21}{2}\)
= \(\frac{4 \times 22 \times 3}{30} \times \frac{88}{10}\) = 8.8cm
Perimeter = 8.8 + 2r = 8.8 + 2r
= 8.8 + 2(10.5)
= 8.8 + 21
= 29.8cm
What is the product of \(\frac{27}{5}\), \((3)^{-3}\) and (\(\frac{1}{5})^{-1}\)?
- A. 5
- B. 3
- C. 1
- D. \(\frac{1}{25}\)
Correct Option: Answer is C
\(\frac{27}{5} \times 3^{-3} \times \frac{(1)^{-1}}{5}\)
= \(\frac{27}{5} \times \frac{1}{3^3} \times \frac{1}{\frac{1}{5}}\)
\(\frac{27}{5}\) x \(\frac{1}{27}\) x \(\frac{5}{1}\) = 1