prob. store gets exactly 1 blue, given random supply of 3

[HeatherBelle09]

A pet supplier has a stock of parakeets of which 10% are blue parakeets. A pet store orders 3 parakeets from this supplier. If the supplier selects the parakeets at random, what is the chance that the pet store gets exactly one blue parakeet?

 

[soroban]

Re: prob. store gets exactly 1 blue, given random supply of

Hello, HeatherBelle09!

A pet supplier has a stock of parakeets of which 10% are blue parakeets.
A pet store orders 3 parakeets from this supplier.
If the supplier selects the parakeets at random,
what is the chance that the pet store gets exactly one blue parakeet?

Answer: \(\displaystyle \L\:{3\choose1}(0.10)(0.90)^2\;=\;0.243\)

 

[Denis]

Hmmm....nature of problem forces # of parakeets = multiples of 10.
Owner takes 3 parakeets at random; isn't probability simply 3/10?
number 10 parakeets 0 to 9; make 6 the blue one:
012,123,234,345,45[6],5[6]7,6[7]8,789,890,901

I'm sure I'm missing something...WHAT?

 

[Deleted member 4993]

You need to assume that the number of parakeets is VERY LARGE.

Thus choosing 3 parakeets - does not change the percentages (effectively). It is like assuming normal distribution after the "specimen size" > 120.

 

[Denis]

You need to assume that the number of parakeets is VERY LARGE.

No thanks Subby, that would be too noisy for me :shock: