Question

What is the probability of three sum being 4

Answer 1

Answer:

Step-by-step explanation:

x1+x2+x3 = 4

(1+x+x^2+x^3+x^4+x^5+x^6)^3 = 4

(1-x^7 / 1-x)^3 = 4

(1-x^7)^3(1-x)^-3 = 4

coeffcient of x^4 in (1-x)^-3

therefore coefficient = 4+3-1 c 2

6c2

15

therefore 15 possibilities

total possibilities = 216

probability = 0.06945