MEBook

Question

Assume that  a fair six-sided die is rolled once. If the value on the die is 1, 2, or 3, the die is rolled a second time.So find the  probability that the aggregate of  total of values that turn up is at least 6?

Answer 1

1.when we get 6 on the first throw =1/6

2.getting 1on the first throw,we need 5 or 6 on the next throw.so 1/6* 1/6 + 1/6*1/6

3.getting 2 on first throw,we need 4 or 5 or 6 on next throw,so 1/6* 1/6   +  1/6* 1/6   +   1/6* 1/6

4.getting 3 on first throw,we need 3 or 4 or 5 or 6 on next throw,so 1/6* 1/6  +  1/6* 1/6  +   1/6* 1/6  + 1/6* 1/6

total probability = 1/6 + 2*1/6* 1/6 + 3*1/6* 1/6  + 4*1/6* 1/6