Please help !! Will medal and fan!!

Alisha bought a collection of 500 old pennies. She chose 20 pennies from the collection and recorded their dates. Seven pennies had dates earlier than 1980.

What percent of the pennies in Alisha’s collection have dates earlier than 1980?

Question

Please help !! Will medal and fan!!

Alisha bought a collection of 500 old pennies. She chose 20 pennies from the collection and recorded their dates. Seven pennies had dates earlier than 1980.

What percent of the pennies in Alisha’s collection have dates earlier than 1980?

mathmale · Answer

This is a bit of an oversimplification.  However, let's go with the assumption that the observed probability of choosing pre-1980 pennies is 7 out of 20, or 7/20, or 0.35.

What do you do with this 0.35?  Re-read the question.

tkhunny · Answer

175 +/- 32  ==> [143,207] ==> [0.286, 0.414] with relatively high confidence

Still a grave oversimplification.