Answer:
P(red) = .3
P(yellow) = .3
75 cubes in the box
Explanation:
The probability has to add to 1
Since the number of red cubes equals the number of yellow cubes the probability has to be the same
.4 + x+x = 1
.4 +2x = 1
2x = 1-.4
2x = .6
Divide by 2
x = .6/2
x = .3
P(red) = .3
P(yellow) = .3
We know that
P(blue) = .4 = number of blue cubes/ total number of cubes
.4 = 30/total
total = 30/.4
total = 75