UPSC Prelims 2021·CSAT·Quantitative Aptitude·Combinatorics and Probability

In a group of 120 persons, 80 are Indians and rest are foreigners. Further, 70 persons in the group can speak English, The number of Indians who can speak English is

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Last updated 23 May 2026, 3:31 pm IST
  1. A20
  2. B30
  3. C30 or less
  4. D30 or moreCorrect

Explanation

Let's break down the problem: 1. Total persons = 120 2. Indians = 80 3. Foreigners = Total persons - Indians = 120 - 80 = 40 4. Persons who can speak English = 70 Let 'X' be the number of Indians who can speak English. To find the minimum possible value for 'X', we assume the maximum possible number of foreigners speak English. * The maximum number of foreigners who can speak English is 40 (since there are only 40 foreigners in total). * If 40 foreigners speak English, then the remaining English speakers must be Indians. * Number of Indians who can speak English = Total English speakers - Foreigners who speak English = 70 - 40 = 30. So, at least 30 Indians must be able to speak English. This means X >= 30. Now let's consider the maximum possible value for 'X'. * The number of Indians who can speak English cannot exceed the total number of Indians (80). * The number of Indians who can speak English cannot exceed the total number of English speakers (70). * Therefore, X <= 70. Combining these, the number of Indians who can speak English (X) is between 30 and 70 (inclusive). 30 <= X <= 70. Let's evaluate the options: * A) 20: This is less than 30, so it's not possible. * B) 30: This is a possible value, but not the full range or description. * C) 30 or less: This contradicts our finding that X must be at least 30. * D) 30 or more: This correctly states the minimum possible number of Indians who can speak English, covering the entire range from 30 up to 70. The final answer is D.
Quantitative Aptitude: In a group of 120 persons, 80 are Indians and rest are foreigners. Further, 70 persons in the group can speak English, T

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