Math Q

NYSpeed Automotive NYSpeed Off Topic
1

One urn contains 3 red and 7 white marbles. A second urn contains 2 red and 8 white marbles. One urn is selected and a ball drawn. The probability of selecting the first urn is 0.4 and the probability of selecting the second is 0.6. If a white ball is drawn, find the probability it came from the second urn:

I would think it is .48 but that is wrong. WTF? Someone smarter explain please.Possible answers.
0.800
0.632
0.560
0.480

For a sample of size n = 60, proportion p = 0.35, and at a 95% confidence level, the lower bound of the proportion is _____.

This one i have no clue what they are even asking me. None of my ideas even come close to any of the possible answers.
0.229
0.121
0.175
0.414

2

how are they taking two urns and saying that the probability is .4 and .6? should that be a given at .5 & .5 to begin with?? I havent had to take a math class in like 4 years so maybe i am way off / just dont care.

3

Maybe one is more appealing IDK lol. I thought it would just be .8(being white marbles in 2nd urn)x.6(the probability of picking that urn).

4

is it .6

5

0.800
0.632
0.560
0.480
These are the options.

6

logically the probability of it coming from the second urn is > thatn the first. the second had a higher rate of selection (.6) and it also has more white and less red than the first. .48 is a bad answer

7

IDK its really not that hard

8

Edited with a second question. I would like a soild explination please not just an answer as i would like to know why.

9

All of the above

10

Thats not helping assface.