Question

What is the probability that a person flipping a fair coin requires four tosses to get a head?

Answer 1

This is the probability of getting tails on first three tosses, then heads.

Answer 2

P(TTTH)

Answer 3

Therefore, the answer is 1/16. But the answer on the book is 1/4. I don't quite get that.

Answer 4

A similar question was also with it. The problem where you will have exctly one heads after 4 tosses. The answer indicated in the book was 1/16 which is P(TTH)

Answer 5

I'm not sure why it does not work.

Answer 6

Are you sure? Because these answer should be the other wat\y.

Answer 7

way*

Answer 8

the second question actually wasn't exactly like that.. Here is the second question whose answer indicated in the book was 1/16


"Suppose an experiment consists of tossing a fair coin until three heads
occur. What is the probability that the experiment ends after exactly six
flips of the coin with a head on the fifth toss as well as on the sixth"

The answer for the 1st question was 1/4 (indicated). It only showed the answer, no solutions.

Answer 9

You have trouble understanding why answer for second question is 1/16?

And what is first question exactly?

Answer 10

the probability of getting a head after four tosses... was just comparing the two of them since i still don't know how to differentiate the two.

Answer 11

**the probability that the first head will occur on the 4th toss of the coin

Answer 12

P(H|TTT) = P(H n TTT)/P(TTT)

seems kinda pointless eh

Answer 13

it could be that your book is just full of errors :)

Answer 14

I used the pdf for geometric distribution in the (1st) question and got 1/16 as well. Was wondering why I got the wrong answer.

Answer 15

first question is geometric distribution. first head at fourth toss means the first three tosses are tails : 1/2*1/2*1/2 and the last toss is head : 1/2
since each trial is independent, probability of getting a head at fourth toss would be 1/2^4 = 1/16

textbook answer is wrong

Answer 16

so I should just stick to 1/16 then? I have an exam later and this helped a lot :) thanks for the enlightenment and for the concepts you guys taught me :D

Answer 17

Yes 1/16 is right

Answer 18

`Suppose an experiment consists of tossing a fair coin until three heads occur. What is the probability that the experiment ends after exactly six flips of the coin with a head on the fifth toss as well as on the sixth`

first fix fifth and 6th results. probability of occuring heads on fifth and sixth tosses is 1/2*1/2 = 1/4