Answer:
99/512 = 0.193359375
Step-by-step explanation:
Each sequence of 5 H's and 7 T's has probability of occurring equal to 1/2^12 (1 divided by 2 to the twelfth power).
Since the number of 5 H, 7 T sequences is equal to C(12,5) = the number of combinations of 12 things taken 5 at a time =
12 * 11 * 10 * 9 * 5 / (5 * 4 * 3 * 2 * 1) =
792,
we have that the probability of obtaining 5 H's and 7 T's =
the sum of the probabilities of all of the sequences =
1/2^12 + 1/2^12 + 1/2^12 + . . . + 1/2^12, 792 times =
792(1/2^12) =
99 / 2^9 =
99 /512 =
0.193359375
