For one toss of a certain coin, the probability that the outcome is heads is 0.6. If this coin is tossed 5 times, which of the following is the probability that the outcome will be at least 4 times?

a. 0.6^5
b. 2(0.6)^4
c. 3(0.6)^4 (0.4)
d. 4(0.6)^4 (0.4) + (0.6)^5
e. 5(0.6)^4 (0.4) + (0.6)^5

ok... I got the (0.6)^4 (0.4) + (0.6)^5 using "cases." However, I do not understand why the "5" is needed for the answer to be correct. Could you explain?

Thank you!

[kevin]

Simply because we need to consider
THHHH, HTHHH, HHTHH, HHHTH, HHHHT

Oh.... because the (0.6)^4 (0.4) is for one instance of 4 heads and 1 tail, when I needed to consider all five posibilities. Thank you!