Please help with this probability question!

[katieTX]

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I got this question wrong in Barron Model A Exam but they have not explaination for it. Please help.

A bowl contains 7 blue and 3 red marbles. What is the probability that 2 marbles selected at random from this bowl without replacement are both red?

I'm here waiting for reply 🙂 Mucho gracias1

 

[chordata]

Probability =
3 red out of 10 = 3/10 for first draw
2 red out of 9 = 2/9 for second draw

Total Probablity = 3/10 * 2/9 = 6/90 = 1/15

 

[katieTX]

i got it now. thanks a ton!!!

Probability =
3 red out of 10 = 3/10 for first draw
2 red out of 9 = 2/9 for second draw

Total Probablity = 3/10 * 2/9 = 6/90 = 1/15