Question

Mr. and Mrs. Doran have a genetic history such that the probability that a child being born to them with a certain trait is 1/4. If they have seven children, what is the probability that exactly six of their seven children will have that trait? Round your answer to the nearest thousandth.

Answer 1

The probability of an event, p, occurring exactly r times:

n Cr .pr . qn-r
Binomial Probability-1
n = number of trials
r = number of specific events you wish to obtain
p = probability that the event will occur
q = probability that the event will not occur
(q = 1 – p, the complement of the event)

Answer 2

p = 1/4
q = 1-1/4 = 3/4
n = 7
r = 6
C(n,r) = n!/ [ r!(n-r)! ] = 7!/ [6!*1*] = 7
7 * (1/4)^6 ( 3/4)^1
= 7 * 0.00024 * .75
= 0.00128

Answer 3

I copied
screwy notation
better
nCr * p^r * q^ (n-r)