22 Solve for all values of x:
2
=
x
+
x
1
23 Mr. and Mrs. Doran have a genetic history such that the probability
1
that a child being born to them with a certain trait is . If they have
8
four children, what is the probability that exactly three of their four
children will have that trait?
[9]
[OVER]
Math. B – Aug. ’07