# Thread: Don't know what formula to use...

1. ## Don't know what formula to use...

I need help with this problem. Don't know which formula to use and where to start. Please help....

It has been estimated that about 30% of frozen chicken contain enough salmonella bacteria to cause illness if improperly cooked. A consumer purchases 15 frozen chickens. What is the probability that the consumer will have less than 3 contaminated chickens? Round to 3 decimal places.

2. Originally Posted by vedmachka
I need help with this problem. Don't know which formula to use and where to start. Please help....

It has been estimated that about 30% of frozen chicken contain enough salmonella bacteria to cause illness if improperly cooked. A consumer purchases 15 frozen chickens. What is the probability that the consumer will have less than 3 contaminated chickens? Round to 3 decimal places.
Use the binomial distribution.

$n = 15$, $p = 0.3 \implies q = 0.7$. you want $P(X < 3) = P(0) + P(1) + P(2)$

3. ## Sorry...

Thank you so much for the formula, but I don't know how to solve that.

4. Originally Posted by vedmachka
Thank you so much for the formula, but I don't know how to solve that.
i told you the formula and gave you the parts, it is just plug and chug from here. where are you stuck?

see post #2 here

and here

and here

and post #34 here