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.
<pre>
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</pre>