Question

A bag contains 950 marbles. Some are red and some are blue. A student reached into the bag

and pulled out a random sample of 20 marbles. He recorded that 11 were blue and 9 were
red. If this is a representative sample, about how many marbles out of 950 are blue?

Answer 1

Answer: The number of blue marbles in the sample is 11, so the proportion of blue marbles in the sample is 11/20. If the sample is representative, we can use this proportion to estimate the proportion of blue marbles in the whole bag of 950 marbles. So, our estimate of the number of blue marbles in the whole bag is:

950 * (11/20) = 477.5

So, we can estimate that about 478 marbles out of 950 are blue.

Explanation: