SOLUTION: Mr. and Mrs. Doran have a genetic history such that the probability that a child being born to them with a certain trait is 87%. If they have seven children, what is the probabil

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Question 1156344: Mr. and Mrs. Doran have a genetic history such that the probability that a child
being born to them with a certain trait is 87%. If they have seven children,
what is the probability that at least four of their seven children will have
that trait? Round your answer to the nearest thousandth.

Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
Mr. and Mrs. Doran have a genetic history such that the probability that a child
being born to them with a certain trait is 87%. If they have seven children,
what is the probability that at least four of their seven children will have
that trait? Round your answer to the nearest thousandth.
There are two ways to do it with a TI-83 or 84

FIRST WAY:

The complement event is that 3 or fewer will have that trait. 

Press 2ND VARS and scroll down to binomcdf(, [careful, not binompdf(]

that's 7 trials, p=0.87, x value 3

Should have on your screen

binomcdf(7,0.87,3)

press ENTER

0.0072028157

Subtract from 1.

1-0.0072028157

0.9927971843  round to 0.993

--------------------------------

SECOND WAY

That's the same thing as 3 or fewer will not have the trait.
The probability of not having the trait is 1-0.87=0.13.

Press 2ND VARS and scroll down to binomcdf(, [careful, not binompdf(]

that's 7 trials, p=0.13, x value 3

Should have on your screen

binomcdf(7,0.13,3)

press ENTER

0.9927971843  round to 0.993

Edwin