Probability Word Problem

Question

As part of a 6th grade class project, the teacher brings to class a large jar containing 200 gumballs of two different colors; red and green. Andy is asked to draw a sample of his own choosing and estimate the number of red gumballs in the jar. Andy draws a sample of 20 gumballs, of which 7 are red, and 13 are green. Use Andy's sample to estimate the number of red gumballs in the jar.

Answer 1

7 red gumballs out of 20 were pulled, therefore

7 / 20

And since this is an estimate of about 200 gumballs:

7 /20 = x / 200

 

Now we multiply both sides by 200:

7 * 200 / 20 = x

7 * 10 / 1 = x

70 / 1 = x

70 = x

 

There are about 70 red gumballs in the jar.