About Chanda Walker Expertise I can answer word problems involving mathematics at the high school and college level. I particularly enjoy calculus word problems. Please don't just type the math problem without comments. If you don't tell me what problem your having, I can't help.
Experience Have done word problems as a tutor and as a student of mathematics and physics for years.
Organizations Sigma Xi
Education/Credentials Optical Science PhD
Past/Present Clients I've answered hundreds of questions here at AllExperts.com in algebra, physics and general math sections.
Question A bag contains five red marbles, three green marbles, and four blue marbles.
How many green marbles must be added to the bag so that the probability of
drawing a green marble is 3/4?
Hi, can you please help me? I know the answer is 24 green marbles.
24/32=3/4, but I don't know how to get there. Thank you.
Answer Probability of draw a marble of "whatever" color is:
# of marble's that have that color divided by all the marbles.
So for green:
we have 3 green marbles
we have 12 total marbles
the probability of drawing a green is : 3/12 or 1/4
Now if you want to INCREASE it up to 3/4 then we need to add green marbles. But how many?
let number of green marbles be (3+x) where x is the number of marbles added.
Now, the total number will increase too. 12 + x is the total.
The ratio is now:
(3+x)/(12+x)
And we want that to equal 3/4
(3+x)/(12+x) = 3/4 (let's cross multiply to get rid of denominators)
4*(3+x) = 3*(12+x)
12 + 4x = 36 + 3x
x = 24
You need to add 24 green marbles. The ratio would then be 24/32 or 3/4.
