Percentage problems
- 1. What percentage of numbers from 1 to 70 have 1 or 9 in the unit's digit?
Options- A. 1
- B. 14
- C. 20
- D. 21 Discuss
Correct Answer: 20
Explanation:
Clearly, the numbers which have 1 or 9 in the unit's digit, have squares that end in the digit 1. Such numbers from 1 to 70 are 1, 9, 11, 19, 21, 29, 31, 39, 41, 49, 51, 59, 61, 69.
Number of such number =14
| ∴ Required percentage = | ❨ | 14 | x 100 | ❩% = 20%. |
| 70 |
- 2. In an election between two candidates, one got 55% of the total valid votes, 20% of the votes were invalid. If the total number of votes was 7500, the number of valid votes that the other candidate got, was:
Options- A. 2700
- B. 2900
- C. 3000
- D. 3100 Discuss
Correct Answer: 2700
Explanation:
Number of valid votes = 80% of 7500 = 6000.
∴ Valid votes polled by other candidate = 45% of 6000
| = | ❨ | 45 | x 6000 | ❩ | = 2700. |
| 100 |
- 3. Two numbers A and B are such that the sum of 5% of A and 4% of B is two-third of the sum of 6% of A and 8% of B. Find the ratio of A : B.
Options- A. 2 : 3
- B. 1 : 1
- C. 3 : 4
- D. 4 : 3 Discuss
Correct Answer: 4 : 3
Explanation:
| 5% of A + 4% of B = | 2 | (6% of A + 8% of B) |
| 3 |
| ⟹ | 5 | A + | 4 | B | = | 2 | ❨ | 6 | A + | 8 | B | ❩ |
| 100 | 100 | 3 | 100 | 100 |
| ⟹ | 1 | A + | 1 | B | = | 1 | A + | 4 | B |
| 20 | 25 | 25 | 75 |
| ⟹ | ❨ | 1 | - | 1 | ❩ A = | ❨ | 4 | - | 1 | ❩ B |
| 20 | 25 | 75 | 25 |
| ⟹ | 1 | A = | 1 | B |
| 100 | 75 |
| A | = | 100 | = | 4 | . |
| B | 75 | 3 |
∴ Required ratio = 4 : 3
- 4. Gauri went to the stationers and bought things worth Rs. 25, out of which 30 paise went on sales tax on taxable purchases. If the tax rate was 6%, then what was the cost of the tax free items?
Options- A. Rs. 15
- B. Rs. 15.70
- C. Rs. 19.70
- D. Rs. 20 Discuss
Correct Answer: Rs. 19.70
Explanation:
Let the amount taxable purchases be Rs. x .
| Then, 6% of x = | 30 |
| 100 |
| ⟹ x = | ❨ | 30 | x | 100 | ❩ = 5. |
| 100 | 6 |
∴ Cost of tax free items = Rs. [25 - (5 + 0.30)] = Rs. 19.70
- 5. A student multiplied a number by 3⁄5 instead of 5⁄3. What is the percentage error in the calculation?
Options- A. 34%
- B. 44%
- C. 54%
- D. 64% Discuss
Correct Answer: 64%
Explanation:
Let the number be x.
| Then, error = | 5 | x - | 3 | x = | 16 | x. |
| 3 | 5 | 15 |
| Error% = | ❨ | 16x | x | 3 | x 100 | ❩% = 64%. |
| 15 | 5x |
- 6. A batsman scored 110 runs which included 3 boundaries and 8 sixes. What percent of his total score did he make by running between the wickets?
Options- A. 45%
- B. 45 5⁄11%
- C. 54 6⁄11%
- D. 55% Discuss
Correct Answer: 45 5⁄11%
Explanation:
Number of runs made by running = 110 - (3 x 4 + 8 x 6)
= 110 - (60)
= 50.
| ∴ Required percentage = | ❨ | 50 | x 100 | ❩% = 45 | 5 | % |
| 110 | 11 |
- 7. Two tailors X and Y are paid a total of Rs. 550 per week by their employer. If X is paid 120 percent of the sum paid to Y, how much is Y paid per week?
Options- A. Rs. 200
- B. Rs. 250
- C. Rs. 300
- D. None of these Discuss
Correct Answer: Rs. 250
Explanation:
Let the sum paid to Y per week be Rs. z .
Then, z + 120% of z = 550.
| ⟹ z + | 120 | z = 550 |
| 100 |
| ⟹ | 11 | z = 550 |
| 5 |
| ⟹ z = | ❨ | 550 x 5 | ❩ = 250. |
| 11 |
- 8. Two students appeared at an examination. One of them secured 9 marks more than the other and his marks was 56% of the sum of their marks. The marks obtained by them are:
Options- A. 39, 30
- B. 41, 32
- C. 42, 33
- D. 43, 34 Discuss
Correct Answer: 42, 33
Explanation:
Let their marks be ( x + 9) and x .
| Then, x + 9 = | 56 | (x + 9 + x) |
| 100 |
⟹ 25(x + 9) = 14(2x + 9)
⟹ 3x = 99
⟹ x = 33
So, their marks are 42 and 33.
- 9. Rajeev buys good worth Rs. 6650. He gets a rebate of 6% on it. After getting the rebate, he pays sales tax @ 10%. Find the amount he will have to pay for the goods.
Options- A. Rs. 6876.10
- B. Rs. 6999.20
- C. Rs. 6654
- D. Rs. 7000 Discuss
Correct Answer: Rs. 6876.10
Explanation:
| Rebate = 6% of Rs. 6650 = Rs. | ❨ | 6 | x 6650 | ❩ | = Rs. 399. |
| 100 |
| Sales tax = 10% of Rs. (6650 - 399) = Rs. | ❨ | 10 | x 6251 | ❩ | = Rs. 625.10 |
| 100 |
∴ Final amount = Rs. (6251 + 625.10) = Rs. 6876.10
- 10. If 20% of a = b, then b% of 20 is the same as:
Options- A. 4% of a
- B. 5% of a
- C. 20% of a
- D. None of these Discuss
Correct Answer: 4% of a
Explanation:
| 20% of a = b ⟹ | 20 | a = b. |
| 100 |
| ∴ b% of 20 = | ❨ | b | x 20 | ❩ | = | ❨ | 20 | a x | 1 | x 20 | ❩ | = | 4 | a = 4% of a. |
| 100 | 100 | 100 | 100 |
More in Aptitude:
Programming
Copyright ©CuriousTab. All rights reserved.