Question

A couple has one or two or three children with probability (1)/(4) (1)/(2) and (1)/(4) respectively.Probability of a couple having exactly four grandchildren in such a type of society is (p)/(q) then sum of digit of q equals. (Where p&q are co-prime natural numbers)​

Answer 1

Answer:

Answer is 127 please check it ......

Answer 2

Answer: 27/128 is the probability of having 4 grandchildren.

Step-by-step explanation:

Let A be the 1st child then, P(A)=1/4

Let B be the two children, P(B)=1/2
Let C be the three children, P(C)=1/4

Let D be 4 grandchildren, P(D)

$P(D)=P(A\cap D)+P(B\cap D)+P(C\cap D)$

• If the couple has one child, the probability of having 4 grandchildren will be equal to zero.
• If the couple has 2 children, there are three probabilities (1,3);(3,1);(2,2)
• If the couple has three children, there are three probabilities (1,1,2);(1,2,1);(2,1,1)

$P(D)=1/4\times 0 +1/2(1/4\times 1/4+1/4\times 1/4+1/4\times 1/4+1/2\times 1/2)+1/4(1/4\times 1/4\times 1/2+1/4\times 1/2\times 1/4+1/2\times 1/4\times 1/4)\\P(D)=27/128$

The probability of having 4 grandchildren is 27/128.