Learn in your speed, with individual attention - Teachoo Maths 1-on-1 Class

Ex 13.1

Ex 13.1, 1

Ex 13.1, 2

Ex 13.1, 3 Important

Ex 13.1, 4

Ex 13.1, 5

Ex 13.1, 6 (i)

Ex 13.1, 6 (ii) Important

Ex 13.1, 6 (iii)

Ex 13.1, 7 (i)

Ex 13.1, 7 (ii)

Ex 13.1, 8

Ex 13.1, 9

Ex 13.1, 10 (a) Important

Ex 13.1, 10 (b) Important

Ex 13.1, 11

Ex 13.1, 12 Important

Ex 13.1, 13 Important You are here

Ex 13.1, 14

Ex 13.1, 15

Ex 13.1, 16 (MCQ) Important

Ex 13.1, 17 (MCQ) Important

Chapter 13 Class 12 Probability

Serial order wise

Last updated at Aug. 16, 2023 by Teachoo

Ex 13.1, 13 An instructor has a question bank consisting of 300 easy True / False questions, 200 difficult True / False questions, 500 easy multiple choice questions and 400 difficult multiple choice questions. If a question is selected at random from the question bank, what is the probability that it will be an easy question given that it is a multiple choice question? Let Easy questions be denoted by E, Difficult questions be denoted by D, MCQ’s be denoted by M & True/False questions be denoted by T Given, E ∩ T = 300 , D ∩ T = 200 , E ∩ M = 500 , D ∩ M = 400 We need to find the probability that it will be an easy question, given that it is a MCQ. i.e. P(E | M) Now, P(E ∩ M) = Probability that question is Easy MCQ = (𝑇𝑜𝑡𝑎𝑙 𝐸𝑎𝑠𝑦 𝑀𝐶𝑄 𝑄𝑢𝑒𝑠𝑡𝑖𝑜𝑛𝑠)/(𝑇𝑜𝑡𝑎𝑙 𝑞𝑢𝑒𝑠𝑡𝑖𝑜𝑛𝑠) = 500/1400 = 𝟓/𝟏𝟒 And, P(M) = (𝑇𝑜𝑡𝑎𝑙 𝑀𝐶𝑄 𝑞𝑢𝑒𝑠𝑡𝑖𝑜𝑛𝑠)/(𝑇𝑜𝑡𝑎𝑙 𝑞𝑢𝑒𝑠𝑡𝑖𝑜𝑛𝑠) = (500 + 400 )/1400 = 900/1400 = 𝟗/𝟏𝟒 Thus, P(E | M) = (𝑃(𝐸 ∩ 𝑀))/(𝑃(𝑀)) = (𝟓/𝟏𝟒)/(𝟗/𝟏𝟒) = 5/14 × 14/9 = 𝟓/𝟗 ∴ Required probability is 𝟓/𝟗