Question 22 (B) How many positive three digit integers have the hundredths digit 8 and unit’s digit 5? Find the probability of selecting one such number out of all three digit numbers.Three digit numbers are From 100 to 999 Total number of 3 digit numbers = 999 − 100 + 1 = 900 Now, three digit integers have the hundredths digit 8 and unit’s digit 5 Possible 3 digit numbers with hundredths digit 8 & unit’s digit 5 are 805, 815, 825, 835, 845, 855, 865, 875, 885, 895 Thus, Required number of 3-digit numbers = 10 Now, Required probability = (𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 3 𝑑𝑖𝑔𝑖𝑡 𝑛𝑢𝑚𝑏𝑒𝑟𝑠)/(𝑇𝑜𝑡𝑎𝑙 3 𝑑𝑖𝑔𝑖𝑡 𝑛𝑢𝑚𝑏𝑒𝑟𝑠) = 10/900 = 𝟏/𝟗𝟎

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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

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