Question

In an effort to check the quality of their cell​ phones, a manufacturing manager decides to take a random sample of 10 cell phones from​ yesterday's production​ run, which produced cell phones with serial numbers ranging​ (according to when they were​ produced) from 80800099000 to 80800099999. Assume that each of the 1000 phones is equally likely to be selected. ​

a) What distribution would they use to model the​ selection? ​

b) What is the probability that a randomly selected cell phone will be one of the last 114114 to be produced. ​

c) What is the probability that the first cell phone selected is either from the last 151151 to be produced or from the first 4646 to be produced.

Answer 1

(A) A uniform distribution should be used to model the selection.

(B) # It seems 114 repeated two times because it can not be more than 1000

P(last 114 cell phones)=?

given total number of phones = 1000

P(last 114 cell phones) = 114/1000 = 0.114 (Ans)

(C) # again 151 and 46 repeated two times

We need to calculate P(either last 151 or first 46)

P(either last 151 or first 46) = P(last 151) + P(first 46)

P(last 151) = 151/1000 = 0.151

P(first 46) = 46/1000 = 0.046

P(either last 151 or first 46) = 0.151 + 0.046= 0.197 (Ans)

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