Posted by **Twg** on Saturday, August 8, 2009 at 1:55pm.

a bag contains 7 red chips and 10 blue chips. Two chips are selected randomly without replacement from the bag. what is the probability that both chips are red??

- MATH Prob. -
**PsyDAG**, Saturday, August 8, 2009 at 2:01pm
Work similar to two black cards problem in previous post.

- MATH Prob. -
**Twg**, Saturday, August 8, 2009 at 2:06pm
but how is the answer in decimals??

- MATH Prob. -
**Marth**, Saturday, August 8, 2009 at 2:11pm
You can convert between fractions and decimals - the important part of this question is finding the probability.

Try finding the probability, in either format, and we will be happy to critique your work or help you convert answer formats.

- MATH Prob. -
**Twg**, Saturday, August 8, 2009 at 2:16pm
I don't understand.

- MATH Prob. -
**Marth**, Saturday, August 8, 2009 at 2:41pm
The total number of chips in the bag is 7+10 = 17.

The probability of drawing a red chip the first time is (# of red chips)/(total # chips) = _____________

The probability of drawing a red chip the second time, with no replacement, means that you should assume 1 red chip was removed the first time.

The probability of drawing a red chip the second time = (# of red chips -1)/(total # of chips) = ____________

Multiply the two probabilities together to get your final answer.

- MATH Prob. -
**Twg**, Saturday, August 8, 2009 at 11:46pm
I still do not get it.

I took (7-1)/17= and I got 0.352

but the answers that I have to choose from are

a) 0.485

b) 0.154

C) 0.515

D) 0.548

I am lost!!!

- MATH Prob. -
**PsyDAG**, Sunday, August 9, 2009 at 11:21am
You need to use the *two* probabilities, 7/17 and (since one red has been removed) 6/16. The probability of *both* occurring is found by *multiplying* the probabilities of the individual events. Try it, and one answer will pop out for you.

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