# Thread: probability::tree diagram ::argent H.W

1. ## probability::tree diagram ::argent H.W

John tries to repair a broken toy.Each time he tries the probability that he succeeds is 0.8 .Each time he fails he tries again...

(a) Copy and complete the tree diagram below:

1st try
0.8 ــــــــــــــ succeeds
0.2 ــــــــــــــ fails

2nd try

.... ــــــــــــــ succeeds
.... ــــــــــــــ fails

3rd try

.... ــــــــــــــ succeeds
.... ــــــــــــــ fails

(b) Find the probability that, to succeed, it takes

(i) exactly two tries,

(ii) one,two or three tries,

(iii) exactly five tries

(c) Write down a formula for the probability that he has not succeeded after n tries.

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plz help me in these problem

and i wanna da answer with da steps plz......

2. Originally Posted by elmysterio
John tries to repair a broken toy.Each time he tries the probability that he succeeds is 0.8 .Each time he fails he tries again...

(a) Copy and complete the tree diagram below:

1st try
0.8 ــــــــــــــ succeeds
0.2 ــــــــــــــ fails

2nd try

.... ــــــــــــــ succeeds
.... ــــــــــــــ fails

3rd try

.... ــــــــــــــ succeeds
.... ــــــــــــــ fails

(b) Find the probability that, to succeed, it takes

(i) exactly two tries,

(ii) one,two or three tries,

(iii) exactly five tries

(c) Write down a formula for the probability that he has not succeeded after n tries.

------------------

plz help me in these problem

and i wanna da answer with da steps plz......
With a tree diagram you multiply along the branches and add down each event. As a check the sum of each event must be 1.

Let A=success and B=failure

i)The chance of taking two goes is BA = 0.2*0.8

ii) The chance of taking 1, 2 or 3 tries is 1 minus the chance of not succeeding in three goes. (1-0.2^3)

iii) Same as i) but with 4 failures instead of 1 (0.2^4 * 0.8)

B) The chance of not succeeding means he fails each time which will be 0.2^n for n tries

3. thank u so so much

i needed to solve this problem

thx alot