# binomal probability

• Nov 7th 2007, 12:27 AM
0123
binomal probability
probability to be fined= 0.22

suppose the employee irregularly parks on 7 deliveries, what is probab that is not fined??

$X \sim Bi(n, \theta)$
$X \sim Bi(7, 0.78)$ where 7 is the number of times the "experiment" is repeated, i.e. the number of time the employee parks irregularly and 0.78 is the probability that the driver is not fined (1-0.22).
$P(X=x) = {{n}\choose {x}}\theta^{x}(1-\theta)^{n-x}$
$P(X=7) = {{7}\choose {7}}\ 0.78^7 = 0.78^{7}$
Alternatively just understand that if the employee parks 7 times with probability 0.78 of not getting fined you can work out the total probability by simply calculating $0.78^{7}$.