UPSC Prelims 1998 · General Studies
Question 144: Basic Numeracy
There are 50 students admitted to a nursery class. Some students can speak only English and some can speak only Hindi. Ten students can speak both English and Hindi. If the number of students who can speak English is 21, then how many students can speak only Hindi and how many can speak only English?
AnswerThe answer is (d).
Ten students speak both languages. English speakers number 21, so those who speak only English are 21 - 10 = 11. Everyone speaks at least one language, so 50 - 11 = 39 speak Hindi, and those who speak only Hindi are 39 - 10 = 29. The three numbers asked for, Hindi speakers, only Hindi and only English, are 39, 29 and 11.
How you could have got this
No shortcut here: in a “how many” question, ruling out options doesn’t help. Every statement has to be judged.
This follows an unofficial answer: UPSC has not published its key for this year, and if that answer is wrong, so is this path.
Which options go is worked out from UPSC’s key and the options, not by a model.
Why each option is right or wrong
- (a) Only-English of 29 would make the English total 39, not 21.
- (b) 28, 18 and 22 give an English total of 32, not 21.
- (c) 37, 27 and 13 give an English total of 23, not 21.
- (d) Right: 39 Hindi speakers, 29 only Hindi, 11 only English.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 1998, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.