### Exercise :: Arithmetic Reasoning - Section 1

- Arithmetic Reasoning - Section 1
- Arithmetic Reasoning - Section 2

21. | In a class, there are 18 boys who are over 160 cm tall. If these constitute three-fourths of the boys and the total number of boys is two-thirds of the total number of students in the class, what is the number of girls in the class ? |
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Answer: Option B Explanation: Let the number of boys be x. Then, (3/4)x = 18 or x = 18 x(4/3) = 24. If total number of students is y, then (2/3) y = 24 or y = 24 x (3/2) = 36. Therefore Number of girls in the class = (36 - 24) = 12. |

22. | A father is now three times as old as his son. Five years back, he was four times as old as his son. The age of the son (in years) is |
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Answer: Option B Explanation: Let son's age be x years. Then, father's age = (3x) years. Five years ago, father's age = (3x - 5) years and son's age = (x - 5) years. So, 3x - 5 = 4 (x - 5) 3x - 5 = 4x - 20 x = 15. |

23. | A waiter's salary consists of his salary and tips. During one week his tips were 5/4 of his salary. What fraction of his income came from tips ? |
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Answer: Option D Explanation: |

24. | If you write down all the numbers from 1 to 100, then how many times do you write 3 ? |
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Answer: Option C Explanation: Clearly, from 1 to 100, there are ten numbers with 3 as the unit's digit- 3, 13, 23, 33, 43, 53, 63, 73, 83, 93; and ten numbers with 3 as the ten's digit - 30, 31, 32, 33, 34, 35, 36, 37, 38, 39. So, required number = 10 + 10 = 20. |

25. | If 100 cats kill 100 mice in 100 days, then 4 cats would kill 4 mice in how many days ? |
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Answer: Option D Explanation: |