Question

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Answer 1

for part a, I have: 1/30.
part b, 23/120

Answer 2

Both defective:

Prob pen 1 is defective: 5/25
Prob pen 2 is defective: 4/24

Prob (DD) = 5/25 * 4/24 = 1/5 * 1/6 = 1/30

Answer 3

Prob GD + Prob DG = 20/25 * 5/24 + 5/25* 20/24 = 1/3

Answer 4

I am not sure about this B part of my work.

Answer 5

P(1D and 1 G) = C(2,1)* (20/25)^1 * (5/25)^1 = 8/25

http://www.wolframalpha.com/input/?i=C%282%2C1%29*+%2820%2F25%29%5E1+*+%285%2F25%29%5E1+%3D

Answer 6

Does the order matter?

Answer 7

would it be C(2,1)* (20/25)^1 * (5/24)^1 instead of C(2,1)* (20/25)^1 * (5/25)^1