The equation given in the question has to be answered to the nearest tenth. The only thing that one should be careful about is the cross multiplication part. Other than that there is no difficulty in the given problem. Now let us get down to the equation in the question.
15/30 = n/34
30 * n = 15 * 34
30n = 510
n = 510/30
= 51/3
= 17
So the value of the unknown variable "n" comes out to be 17.
Pretty much, write two problems that equal to 0
Answer:
1/4
Step-by-step explanation:
Let's denote the probabilities as following:
Probability that a teenager has a sister:
P(A) = 12/28
Probability that a teenager has a brother:
P(B) = 7/28
Probability that a teenager has both a sister and a brother:
P(A⋂B) = 3/28
Probability that a selected teenager has a sister also has a brother, or in other words, he/she has a brother, given he/she had a sister:
P(B|A)
Let's apply the formula of conditional probability to work out P(B|A)
P(B|A) = P(A⋂B)/P(A) = (3/28)/(12/28) = (3*28)/(12*28) = 3/12 = 1/4
=> Option C is correct
Hope this helps!
