Question

A lot of 100 watches is known to have 10 defective watches. If 8 watches are selected (one by one with replacement) at random, what is the probability that there will be at least one defective watch? Select the correct answer from above options

Answer 1

Given: Total number of watches = 100 and number of defective watches = 10 So, the probability of selecting a detective watch = 10/100 = 1/10 Now, n = 8, p = 1/10 and q = 1 – 1/10 = 9/10, r ≥ 1 P(X ≥ 1) = 1 – P(x = 0) = 1 – 8C0 (1/10)0(9/10)8 – 0 = 1 – (9/10)8 Therefore, the required probability is 1 – (9/10)8.