Probability ( 1 blue marble and 3 green marbles) = ( Blue, green, green, green) + ( green, blue, green, green) + ( green, green, blue, green) + ( green, green, green, blue) = { (8/13) × (5/12) × (4/11) × (3/10) } + { (5/13) × (8/12) × (4/11) × (3/10) } + { (5/13) × (4/12) × (8/11) × (3/10) } + { (5/13) × (4/12) × (3/11) × (8/10) } = (4/143) + (4/143) + (4/143)+ (4/143) = 16/143
If the answer does not correspond to yours, do tell me. I'll try to correct mine
You can do 9/1 x A
2 x (9/0.5 x B)
9/0.25 x C
so 9A + 36B + 36C
(9 x 50) + (36 x 80) + (36 x 120) = 450 + 2880 + 4320 = $7650
2 gallons... dude just divide by 2, are you sure this is high school math?
15 is 30% percent of 50, so Corey spent 30% of his earnings.
You would have to change the equation so that y is isolated
