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 2 years ago
Probability:
A man is restoring ten old cars, six of them manufactured in \(1955\) and four of them manufactured in \(1962\). When he tries to start them, on average the \(1955\) models will start \(65\) percent of the time and the 1962 models will start \(80\) percent of time. Find the probability that any time:
a) exactly three of the \(1955\) models and one of the \(1962\) model will start.
 2 years ago
Probability: A man is restoring ten old cars, six of them manufactured in \(1955\) and four of them manufactured in \(1962\). When he tries to start them, on average the \(1955\) models will start \(65\) percent of the time and the 1962 models will start \(80\) percent of time. Find the probability that any time: a) exactly three of the \(1955\) models and one of the \(1962\) model will start.

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Mimi_x3
 2 years ago
Best ResponseYou've already chosen the best response.3This is what I got but i dont know why its not right.. \[\tbinom{6}{3} *(0.39)^3+(0.61)^3 + \binom{4}{1} *(0.39)^1*(0.61)^3\]

apoorvk
 2 years ago
Best ResponseYou've already chosen the best response.1Okay yes, so why did you multiply those factorials  He does not have to 'choose' cars  the cars that start up could be any three outta the 6! And also, you multiply together the probabilities for both kinds of cars  since in the end you want 4 cars to start and 6 not to (with their own respective probabilities governing their 'fates'). (and I believe you wanted to 'multiply' the cube of 0.61 over there, and meant '0.20' and '0.80' for the 1962 models)

Mimi_x3
 2 years ago
Best ResponseYou've already chosen the best response.3This is called Binomial Probability related to the Binomial Expansion..

apoorvk
 2 years ago
Best ResponseYou've already chosen the best response.1So your expression should be: \[\large (0.61)^3\times (0.39)^3 \times (0.80) \times (0.20)^3\]

apoorvk
 2 years ago
Best ResponseYou've already chosen the best response.1Yeah I was guessing this was something like Binomial  but I don't know what use multiply the 'combinations' would be in this particular case.

Mimi_x3
 2 years ago
Best ResponseYou've already chosen the best response.3yeah, and i dont think your answer is right..

Mimi_x3
 2 years ago
Best ResponseYou've already chosen the best response.3the binomial expansion: \[(a+b)^n = \binom{n}{r} *(a)^{nr} * (b)^{n}\]

apoorvk
 2 years ago
Best ResponseYou've already chosen the best response.1Anyways, just correct the 'multiplication' sign in your equation and the '0.80' values, and see if that gets you the answer... I am still wondering..

Mimi_x3
 2 years ago
Best ResponseYou've already chosen the best response.3\[\binom{6}{3} *(0.61)^3*(0.39)+\binom{4}{1} *(0.80)^1*(0.20)^3\] apparently not right

apoorvk
 2 years ago
Best ResponseYou've already chosen the best response.1you obviously need to multiply the two probabilities, not add them  think about it.

Mimi_x3
 2 years ago
Best ResponseYou've already chosen the best response.3the answer is \(0.0060\)

apoorvk
 2 years ago
Best ResponseYou've already chosen the best response.1and what do you seem to be getting?

Mimi_x3
 2 years ago
Best ResponseYou've already chosen the best response.3\(0.0453\) man i hate probability; forget it

apoorvk
 2 years ago
Best ResponseYou've already chosen the best response.1I am starting to hate it too ...

Mimi_x3
 2 years ago
Best ResponseYou've already chosen the best response.3lol its horrible; too confusing _
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