Question

In a storeroom,there are 30 blue balls,48 green balls,some red balls and some white balls. there are 3 times as many green balls as red balls and 5 times as many blue balls as white balls.

(a) How many balls are there altogether?
(b) How many balls are left in the room if 7/10 (fraction) of the balls are taken away?
pls help me answer both

Answer 1

7/30

Explanation:

We first have 7 blue and 3 red out of 10, so P(1st ball is red) = 3/10

Now, we have pulled a red ball out of the bag, leaving us with 7 blue and 2 red out of 9 total balls.Then P(2nd ball is blue) = 7/9. Put this together, P(1st red AND 2nd blue) = 3/10⋅7/9 =7/30