SOLUTION: A car firm has two cars, which it hires out day by day. The number of demand for a car on each day is distributed as poison variate with mean 1.5 . 1.calculate the proportion of

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Question 1118652: A car firm has two cars, which it hires out day by day. The number of demand for a car on each day is distributed as poison variate with mean 1.5 .
1.calculate the proportion of days on which neither car is used
2. Calculate the proportion of days on which some demand will be refused

Answer by addingup(3677) About Me  (Show Source):
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Let X denote number of cars hired out per day
Poisson distribution mean = m = 1.5
P(X=x)=(((e^−m)(m^x))/(x!))= (((e^−1.5)(1.5^x))/(x!))
1) P(neither car is used):
P(X=0)=(e^−1.5)(1.5^0)/0.2231
2) P(Some demand is refused ) = P(Demand is more than 2 cars per days)
P(x>2)
=1−P(x≤2)
=1−[P(x=0)+P(x=1)+P(x=2)]
=1−[((e^1.5)(1.5^0)/0!)+ ((e^1.5)(1.5^1)/1!)+((e^1.5)(1.5^2)/2!)]
=1−e^1.5[1+1.5+(2.25/2)]=0.1912
Proportion of days on which neither car is used = 0.2231 = 22.31 %
Proportion of days on which some demand is refused = 0.1912 = 19.12 %