+295 If the probability that a baby born in a certain hospital will speak in the next day is 1/4, what is the probability that at least 2 babies out of a cluster of 5 babies will speak tomorrow?
+118609 If the probability that a baby born in a certain hospital will speak in the next day is 1/4, what is the probability that at least 2 babies out of a cluster of 5 babies will speak tomorrow?
The prob that LESS than 2 will speak is
5C0 * (0.25)^0 * (0.75)^5 + 5C1 * (0.25)^1 * (0.75)^4
= (0.75)^5 + 5 * 0.25 * (0.75)^4
(0.75)^5+5*0.25*(0.75)^4 = 81/128
so the prob that 2 or more will speak is 1- 81/128 = 47/128
