Monday, February 13, 2012

Probability Application?

A man takes either a bus or the subway to work with probabilities 0.3

and 0.7 respectively. When he takes the bus, he is late 30% of the

days, when he takes the subway he is late 20% of the days.

For 10 consecutive workdays, what is the chance he was late for less

than 2 times? What assumptions you need to make in order to answer this

question?Probability Application?
Prob of being late in a certain day=0.3*0.3+0.7*0.2


Prob of being never late in all ten days=(1-0.23)^10


Prob of being late in only one day =(1-0.23)^9 * 0.23


Prob of being late for less than 2 times= 0.073+0.022


Assumption is actually that the probabilities remain constant during the 10 days.

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