Question

The probability of drawing a blue marble from a bag is 2/5 . The probability of drawing a red marble from the bag is 1/5 . What is the probability of drawing a red marble or a blue marble from the bag?

A.2/5


B.4/5


C.2/25


D.3/5

Answer 1

Is it B?

Answer 2

um...

Answer 3

hmmm

Answer 4

P(B)=2/5, P(R)=1/5
\(P(B\cap R)=P(B)+P(R)-P(B\cup R)\)
But since red and blue are independent, \(P(B\cup R)=0\)
so
\(P(B\cap R)=P(B)+P(R)= ? \)

Answer 5

Erratum:
\(P(B\cup R)=P(B)+P(R)−P(B\cap R)\)
But since red and blue are independent, \(P(B\cap R)=0\)
so
\(P(B\cup R)=P(B)+P(R)=?\)

Answer 6

@VivaLaChloe1
Can you work out P(B)+P(R) and try again?

Answer 7

So is it D? @satellite73

Answer 8

@mathmate @tester97

Answer 9

I think its D :\

Answer 10

Me too.

Answer 11

Correct, it's D.

Answer 12

add !

Answer 13

@mathmate a slight typo when you wrote \[P(B\cup R)=0\]

Answer 14

I AM AN IDIOT.I MEANT D NOT B

Answer 15

Ugh i'm so blind

Answer 16

@satellite73
Yes, it wasn't even a "slight" typo. lol Thank you for pointing it out.
I got the cups and caps inverted.
I put up an erratum below. Perhaps next time I just have to delete the mistaken one and start anew! :)