Homework Help: Math

Posted by Helen on Thursday, February 9, 2012 at 4:57pm.

A bucket contains blue balls and yellow balls. the probability of removing two blue balls without replacement is 2/5 and he probability of removing three blue balls without replacement is 1/5. Why must there be two more blue balls then yellow balls? How many red balls were in the bucket. show that b=y+2

Math - Steve, Thursday, February 9, 2012 at 8:56pm
b/(b+y) * (b-1)/(b+y-1) = 2/5
b/(b+y) * (b-1)/(b+y-1) * (b-2)(b+y-2) = 1/5 = 1/2 * 2/5

so,

(b-2)/(b+y-2) = 1/2
2(b-2) = b+y-2
2b-4 = b+y-2
b = y+2

no idea about any red balls, but

(y+2)/(2y+2) * (y+1)/(2y+1) = 2/5

(y+2)/2(2y+1) = 2/5
5y+10 = 8y+4
3y = 6
y=2
so, b=4

4/6*3/5 = 2/5
2/5*2/4 = 1/5
Math - Steve, Thursday, February 9, 2012 at 8:56pm
b/(b+y) * (b-1)/(b+y-1) = 2/5
b/(b+y) * (b-1)/(b+y-1) * (b-2)(b+y-2) = 1/5 = 1/2 * 2/5

so,

(b-2)/(b+y-2) = 1/2
2(b-2) = b+y-2
2b-4 = b+y-2
b = y+2

no idea about any red balls, but

(y+2)/(2y+2) * (y+1)/(2y+1) = 2/5

(y+2)/2(2y+1) = 2/5
5y+10 = 8y+4
3y = 6
y=2
so, b=4

4/6*3/5 = 2/5
2/5*2/4 = 1/5
Math - Steve, Thursday, February 9, 2012 at 9:02pm
b/(b+y) * (b-1)/(b+y-1) = 2/5
b/(b+y) * (b-1)/(b+y-1) * (b-2)(b+y-2) = 1/5 = 1/2 * 2/5

so,

(b-2)/(b+y-2) = 1/2
2(b-2) = b+y-2
2b-4 = b+y-2
b = y+2

no idea about any red balls, but

(y+2)/(2y+2) * (y+1)/(2y+1) = 2/5

(y+2)/2(2y+1) = 2/5
5y+10 = 8y+4
3y = 6
y=2
so, b=4

4/6*3/5 = 2/5
2/5*2/4 = 1/5

Answer this Question

Related Questions

math - A box contains 8 blue balls and 2 red balls. Three balls are selected ...
Probability again - A box contains 6 red balls, 4 blue balls, and 2 green balls...
statistics - Two urns each contain yellow balls and black balls. Urn 1 contains ...
math probability - Four balls are selected at random without replacement from ...
maths - A box contains 20 balls, of which 5 are red, 5 are blue, 5 are white ...
statistics - An urn contains 4 blue balls, 5 yellow balls and 7 red balls. if a ...
probability - Four balls are selected at random without replacement from an urn...
mathematics - a box contains 2 white and 3 blue balls.two balls are picked at ...
College Discrete - An urn contains n > 0 white balls and m > 0 ...
math - Four balls are selected at random without replacement from an urn ...

For Further Reading

First Name:
School Subject:
Answer: