Imagine in your mind that a fair 20-sided die, with faces labled 1,2,3, . . ., 20, is rolled ten times. What is the expected value of the sum of the rolls? A. 20

B. 60

C. 100

D. 105

P.S: This isn't part of the problem but put this link in. https://youtu.be/ub82Xb1C8os

The last choice 1/55

Pr(yellow, red, and black) =  (2/12)*(4/11)*(3/10) = 1/55

Step-by-step explanation:

How many marbles are there total?

3  + 2 + 4 + 3 =  12 total

draw 3 marbles. without replacing

1st marble is yellow, Probability is  2/12

2nd marble is red Probability is 4/11

3rd marble is black Probability is 3/10

the sample space decreases each time we pull a marble.

so the Pr(yellow, red, and black) =  (2/12)*(4/11)*(3/10) = 1/55