Question

SAT MATH Help:
A bag contains 8 white marbles, 8 blue marbles, 7 red marbles, and 6 yellow marbles. What is the least number of marbles that must be drawn from the bag, so that 3 blue marbles will be drawn?

Answer 1

>* least* number of marbles that must be drawn from the bag, so that 3 blue marbles will be drawn?

Do you think that the first three marbles you draw could be blue?

@bodmass

Answer 2

I guess we have to be sure if the first three marbles that we take
out are really blue,which we are not.

Answer 3

The least number of marbles that could be drawn to get BBB is three. The least number that must be drawn to ensure BBB is a different question.

Answer 4

Probability problems are definitely not my thing.

Answer 5

>What is the least number of marbles that must be drawn from the bag, so that 3 blue marbles will be drawn?

It seems that the least number of marbles that must be drawn from the bag to ensure that 3 blue marbles are drawn is the same as the greatest number of marbles that must be drawn from the bag to ensure that 3 blue marbles will be drawn.

There are 21 non-blue marbles so if you drew out those, 3 blue marbles would be left.

I think the difficulty, at least part of that difficulty, is in the wording of the problem.

I'm hoping someone else will come along and share his or her thoughts on the problem.

Just reading this: http://talk.collegeconfidential.com/sat-preparation/1237018-dr-chungs-permutation-help.html gives a sense of the confusion.

Answer 6

The answer is 9. It seems intuitive that the answer should be 3...but 3 is not an option.

Answer 7

The ninth marbles gives the 3 of the same color
They asked for the "least" number of marbles that can be drawn...so shouldn't the answer be 3? I could pick 3 whites. Done.

Answer 8

it would be yellow marbles because you have to subtract 5 from 8 to get 3 when you do the same yellow marble is the smallest one

Answer 9

@ageta The task is not to draw 3 marbles of the same color but to draw three blue marbles.