Posted by Twg on .
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,
Work similar to two black cards problem in previous post.

MATH Prob. 
Twg,
but how is the answer in decimals??

MATH Prob. 
Marth,
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,
I don't understand.

MATH Prob. 
Marth,
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,
I still do not get it.
I took (71)/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,
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.

MATH Prob. 
Anonymous,
2