Question

A bag contains 8 red marbles, 9 yellow marbles, and 7 green marbles. how many additional red marbles must be added to the 24 marbles already in the bag so that the probability of randomly drawing a red marble is 3/5

Answer 1

16

Explanation:

bag red: 8 + x

yellow:9

green 7/24

3/5 = 8+ x/24+ x

5(8 + x) = 3 (24 + x)

40 + 5x

-40 -3x = 72 + 3x

-40 -3x -40 - 30

2x/2 = 32/2 so,x = 16

Answer 2

16 red marbles

Explanation:

8 red

9 yellow

7 green

total = 8 + 9 + 7

p(red) = 8/24 = 1/3

Add r number of red marbles to the total.

8 + r red

9 yellow

7 green

total = 8 + r + 9 + 7 = r + 24

p(red) = (8 + r)/(r + 24) = 3/5

Cross multiply.

40 + 5r = 72 + 3r

2r = 32

r = 16

Answer: 16 red marbles