Question

What is the probability of flipping a coin 10 times and getting tails 7 times ? Round your answer to the nearest tenth of a percent.

Answer 1

Answer:

Option C: 11.7%

Step-by-step explanation:

The number of elements in sample space when a coin is flipped 10 times will be:

$n(S) = 2^{10} \\= 1024$

Let A be the event that the tails appear 7 times:

Then,

$C_{(n,k)}=\frac{n!}{(k!)(n-k)!} \\where\\n=population\\k=picks\\In our case, k =7\\and\\n=10\\C_{(10,7)}= \frac{10!}{(7!)(10-3)!}\\= 120\\So, \\P(A) = \frac{n(A)}{n(S)} \\P(A) = \frac{120}{1024} \\= 0.1171$

Converting into percentage:

$P(A) = 0.1171*100=11.7%$

So, option C is correct ..