The probability of picking a red pencil out of a drawer is 3/11. The only other color of pencil is blue, and there are 16 blue pencils. If 2 red pencils are added, what will be the new probability of picking a blue pencil?

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Answer 1 · 2016-11-20T18:15:55

#"Prob(BLUE)" = 2/3#

There are only two colours of pencil in the drawer.

#"Prob(RED) " = 3/11" " :. "Prob(BLUE)" = 8/11#

But, there are 16 Blue pencils. Make an equivalent fraction.

#8/11 xx2/2 = 16/22#

So, there are 22 pencils in the box, 16 are Blue and 6 are Red.

Now 2 more Red pencils are added.

So, there are now 24 pencils in the box, 16 are Blue and 8 are Red.

#"Prob(BLUE)" = 16/24#

#= 2/3#