Mathematics 2021 Past Questions | WAEC
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.
46. A box contains 40 identical balls of which 10 are red and 12 are blue. If a ball is selected at random from the box, what is the probability that it is neither red nor blue?
- A.9/20
- B. 3/10
- C. 1/4
- D. 11/20
Correct Option: Answer is A
Pr (r)=10/40, Pr(not red) = 30/40
Pr (b)=12/40, Pr(not blue) = 28/40
Pr(r) or P(b) = 10/40 + 12/40 =22/40=11/20
Pr(r) nor P(b) = 1 – 11/20 =9/20 (Mutually Exclusive)
47. A fair die is tossed twice. What is the probability of getting at least 10?
- A. 5/36
- B. 2/3
- C. 5/18
- D. 1/6
Correct Option: Answer is D
| 1 | 2 | 3 | 4 | 5 | 6 |
1 | 1,1 | 1,2 | 1,3 | 1,4 | 1,5 | 1,6 |
2 | 2,1 | 2,2 | 2,3 | 2,4 | 2,5 | 2,6 |
3 | 3,1 | 3,2 | 3,3 | 3,4 | 3,5 | 3,6 |
4 | 4,1 | 4,2 | 4,3 | 4,4 | 4,5 | 4,6 |
5 | 5,1 | 5,2 | 5,3 | 5,4 | 5,5 | 5,6 |
6 | 5,1 | 5,2 | 5,3 | 6,4 | 6,5 | 6,6 |
the probability of getting at least 10 = 6/36 = 1/6
48. A man will be (x + 10) years old in 8 years time. If 2 years ago, he was 63 years, find the value of x
- A. 55
- B. 63
- C. 57
- D.67
Correct Option: Answer is B
man will be (x + 10) years old in 8 years’ time.
2 years ago, he was 63 years.
Today, he is 63 + 2 =65
8 years from now, he will be 65+8=73
So, he will be (x + 10) years old when he is 73
As a result, x+10=73
X=73-10= 63
49. The equation of a line is given as 3x – 5y = 7. Find its gradient (slope).
- A. 5/3
- B. 3/5
- C. -3/5
- D. -5/3
Correct Option: Answer is B
50. For what value of x 4-2x/x+1 undefined?
- A. 22
- B. 24
- C. 36
- D. 26
Correct Option: Answer is B
X+1= 0; x= -1