SOLUTION: On a single train journey there is a probability of 0.4 that your ticket will be checked. You make a return-journey, what is the probability that your ticket will be checked only o
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Question 1018104: On a single train journey there is a probability of 0.4 that your ticket will be checked. You make a return-journey, what is the probability that your ticket will be checked only once?
Give your answer as a proportion, rounding to two decimal places. Answer by Theo(13342) (Show Source):
the probability of the bags not being checked is therefore 1 - .4 = .6.
the total probabilities are as follows:
probability of bags being checked going only is .4 * .6 = .24
probability of bags being checked coming back only is .6 * .4 = .24
probability of bags being checked both ways is .4 * .4 = .16
probability of bags not being checked both ways is .6 * .6 = .36
total probability is 1 as it should be.
since the probability they will be checked going is .24 and the probability they will be checked coming back is .24, then the probability they will be checked either going or coming is .24 + .24 = .48.
