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Question 1 - Past Year MCQ - Chapter 15 Class 10 Probability (Term 1)

Last updated at Nov. 19, 2021 by

Question 1

A box contains 90 discs, numbered from 1 to 90.Β  If one disc is drawn at random from the box, theΒ  probability that it bears a prime-number less thanΒ  23, is:

(a) 7/90Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β (b) 10/90

(c) 4/45Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β  Β (d) 9/89

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Transcript

Question 1 A box contains 90 discs, numbered from 1 to 90. If one disc is drawn at random from the box, the probability that it bears a prime-number less than 23, is: (a) 7/90 (b) 10/90 (c) 4/45 (d) 9/89 Total number of disks = 90 Prime number less than 23 are… 2, 3, 5, 7, 11, 13, 17, 19 Number of prime numbers less than 23 = 8 Thus, P(getting a prime number less than 23) = (π‘π‘’π‘šπ‘π‘’π‘Ÿ π‘œπ‘“ π‘π‘Ÿπ‘–π‘šπ‘’ π‘›π‘’π‘šπ‘π‘’π‘Ÿπ‘  𝑙𝑒𝑠𝑠 π‘‘β„Žπ‘Žπ‘› 23)/(π‘‡π‘œπ‘‘π‘Žπ‘™ π‘›π‘’π‘šπ‘π‘’π‘Ÿπ‘ ) = 8/90 = πŸ’/πŸ’πŸ“ So, the correct answer is (C)

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.