Sam flips a coin 12 times. Find the probability that it comes up heads at least 10 times.

Guest Jun 8, 2020

#2**0 **

The probability of it being heads 10 times is (1/2)^10, and since we can have cases for 11 and 12, plus (1/2)^11 and (1/2)^12.

So the answer is most definitely not 10/12. An explanation would be helpful?

hugomimihu Jun 8, 2020

#3**+2 **

12! / [10! . 2!. 2^12] =0.01611328125

12! / [11! . 1!. 2^12] =0.0029296875

12! / [12! . 0!. 2^12] =0.000244140625

The probability of at least 10 heads:

**Sum of above 3 =0.019287109375=1.93%, or: 79 / 2^12 =79 / 4096**

Guest Jun 8, 2020