Statistics "Ramdom Sample" Question Help?

Question

100 people who regularly buy eggs are needed to do a survey on a new brand of packaged eggs. After chatting to a random sample of 500 people, we found 75 egg buyers. Then, how many people in a random sample do we need to interview to reach a total of 100 people who regularly buy eggs?

Answer 1

we have seen that 75/500 are egg buyers.  

find n such that

(75 / 500 ) * n = 100

n = 5000/75

n = 666.6666666

we likely need to sample 667 people to get 100 egg buyers

Answer 2

666 and 2/3. its a simple proportion. 500/75=x/100