yeah im a bit confused cuz i got a different value for the 5th roll. i got 324/16807 which is not the same as what the answers say.
Also should i expect all the values in the table to add up to one?
thanks
once you have gone past 4 spins you know that you are on the final spin as the game stops. so to find P ( x = 5 ) you just work out 1 - P ( x < 5 )... in other words add up the previous 4 answers and subtract from 1.
once you have gone past 4 spins you know that you are on the final spin as the game stops. so to find P ( x = 5 ) you just work out 1 - P ( x < 5 )... in other words add up the previous 4 answers and subtract from 1.
ohhh ok
sorry but why is this not the same as the answer you et when you do (3/7)^4 x (4/7)
once you have gone past 4 spins you know that you are on the final spin as the game stops. so to find P ( x = 5 ) you just work out 1 - P ( x < 5 )... in other words add up the previous 4 answers and subtract from 1.
In this case it's probably easier to directly work out P(x > 4) (i.e. P(no G's on previous rolls)).
sorry but why is this not the same as the answer you et when you do (3/7)^4 x (4/7)
(3/7)^4 x (4/7) is the probability of not rolling a G on the first 4 rolls and then rolling a G on the 5th. But you're going to stop after the 5th roll regardless of whether you roll a G on the 5th roll. So you just want (3/7)^4.
In this case it's probably easier to directly work out P(x > 4) (i.e. P(no G's on previous rolls)).
(3/7)^4 x (4/7) is the probability of not rolling a G on the first 4 rolls and then rolling a G on the 5th. But you're going to stop after the 5th roll regardless of whether you roll a G on the 5th roll. So you just want (3/7)^4.
In this case it's probably easier to directly work out P(x > 4) (i.e. P(no G's on previous rolls)).
(3/7)^4 x (4/7) is the probability of not rolling a G on the first 4 rolls and then rolling a G on the 5th. But you're going to stop after the 5th roll regardless of whether you roll a G on the 5th roll. So you just want (3/7)^4.