Approximately, all of the signatures in the sample of 3000 signatures are invalid . We get this outcome by using binomial distribution .
This problem it is said that 30% of 10000 signatures on certain recall petition are invalid . So, here is the two outcomes possible one is the signatures are invalid and other signature are valid .
Probability of Success (signature are valid ) = p = favourable outcomes / total outcomes
Favourable outcomes for Success = 70% of 10,000= 7000
Total number of possible outcomes = 10,000
P = 7000/10,000 = 7/10
Probability of failure (signature are invalid ) = q= 1- p = 1- 7/10 = 3/10
We have to find out probability of getting invalid signature from a sample of 3000 signatures..
Using the binomial distribution,
P(X = x ) = ⁿ C ₓ pˣ (1- p)⁽ⁿ⁻ˣ⁾
n = 3000 , x= 0 for none of signatures from 3000 are invalid.
P(X=0) = ³⁰⁰⁰C ₀ (3/10)⁰ ( 7/10) ³⁰⁰⁰
= 1 . 1 . (7/10)³⁰⁰⁰ = (7/10)³⁰⁰⁰ = 0
Probability of getting invalid signature out of sample 3000 is
1 – ( 7/1000)³⁰⁰⁰ = 1
This implies that all the signatures in sample of 3000 are invalid.
To learn more about binomial distribution, refer:
https://brainly.com/question/14619999
#SPJ4