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!
Assuming the typewriter-looking words are the line names...
1. Line R
2. Line Q (Or R, but it is most likely Q)
3. Points E and F
Collinear Meaning: http://mathworld.wolfram.com/Collinear.html
Combine like terms:
3x-2>5x+10 becomes -12 > 2x
Dividing both sides by 2, we obtain x < -6
Multiply to remove the variable from the denominator.
