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Question 25 (OR 2nd question) - CBSE Class 10 Sample Paper for 2020 Boards - Maths Standard - Solutions of Sample Papers for Class 10 Boards

Last updated at Dec. 16, 2024 by Teachoo

An integer is chosen between 70 & 100, Find the probability that it is

(a) a prime number 

(b) divisible by 7

Note : To see Prime numbers from 1 to 100 , please check

https://www.teachoo.com/7604/2329/Prime-Numbers-from-1-to-100/category/Prime-numbers-from-1-to-100/

Transcript

Question 25 (OR 2nd question) An integer is chosen between 70 & 100, Find the probability that it is (a) a prime number (b) divisible by 7 Since integer is chosen between 70 and 100 Possible numbers to be chosen = 71, 72, 73, 74, …. , 98, 99 Therefore, Total Numbers = (100 – 70) – 1 = 30 – 1 = 29 a prime number Now, Prime numbers between 70 and 100 are 71, 73, 79, 83, 89, 97 Total Prime numbers = 6 Therefore, Probability we have a prime number = (𝑇𝑜𝑡𝑎𝑙 𝑝𝑟𝑖𝑚𝑒 𝑛𝑢𝑚𝑏𝑒𝑟𝑠)/(𝑇𝑜𝑡𝑎𝑙 𝑁𝑢𝑚𝑏𝑒𝑟𝑠) = 𝟔/𝟐𝟗 (b) divisible by 7 Now, Numbers between 70 and 100 divisible by 7 are 77, 84, 91, 98 Total numbers divisible by 7 = 4 Therefore, Probability number is divisible by 7 = (𝑇𝑜𝑡𝑎𝑙 𝑛𝑢𝑚𝑏𝑒𝑟𝑠 𝑑𝑖𝑣𝑖𝑠𝑖𝑏𝑙𝑒 𝑏𝑦 7)/(𝑇𝑜𝑡𝑎𝑙 𝑁𝑢𝑚𝑏𝑒𝑟𝑠) = 𝟒/𝟐𝟗
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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science and Computer Science at Teachoo