Of the 1,000 students in a local college, 420 own brand x mobile phones and 580 own brand y mobile phones. of these students, 80 own both brands of mobile phones. find the probability that a student chosen at random has a brand x mobile phone given that he has a brand y mobile phone.
2/14
5/21
3/28
4/29

The probability that a student chosen at random has a brand X mobile phone given that he has a brand Y mobile phone is 4/29.

Step-by-step explanation:

Since, the total number of students, n(s) = 1,000

The number of students who have X mobile phones, n(X) = 420,

And, number of students who have Y mobile phones, n(Y) = 580,

Thus, the probability of the student that has Y phones,

While, the number of students who have both phones, n(X∩Y) = 80

Thus, the probability of the student who has both phones,

Hence, the probability that a student chosen at random has a brand X mobile phone given that he has a brand Y mobile phone.

Hence, the required probability is 4/29.

50

step-by-step explanation:

step-by-step explanation:

the ratio of red paint to blue paint is always 9/7. that means that, whatever x's value, (4x+12)/(4x-4) has that same ratio. so, set up an equation and cross-multiply to solve for x:

9/7 = (4x+12)/(4x-4)

9(4x-4) = 7(4x+12)

36x - 36 = 28x + 84

8x - 36 = 84

8x = 120

x = 15