jeremy02 wrote:

I'm completely lost on this one, i've been studying for about 4 months and took some time off, now i'm paying for this "vacation", can someone show me the math used to get this answer?

Thanks

The probability of a particular event occurring is the number of outcomes that result in that particular event divided by the total number of possible outcomes.

-In this problem the total number of possible outcomes:

Since there are 2 possible outcomes for each coin toss, (2*2*2*2*2*2) = 64 which is the total number of possible outcomes.

-Now you can use the combination formula to determine the number of outcomes of exactly 2 of the coins landing on heads out of 6 flips.

C(n,r) =n!/(r!(n-r)!) where n = the number of n objects (n=6 flips) taken r (r=2; 2 out of 6 flips landing on heads) at a time.

6!/(2!(6-2)!) = 6!(2!(4!)= 15.

Once again, the probability of a particular event occurring is the number of outcomes that result in that particular event divided by the total number of possible outcomes.

# of outcomes that result in 2 flips out of 6 landing on heads = 15

total # of possible outcomes = 64

15/64 is your answer