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!
8) 5 + 4 + 2 = 11
Since there are 5 guavas, the correct answer is B. 5/11
9) 3 + 4 = 7
Since there are 4 blue papers, the correct answer is A. 4/7
10) Count all of the numbers and add them. There are 4 twos, 2 fives, and 1 three:
4 + 2 + 1 = 7
Since there are 4 twos, the correct answer is C. 4/7
Answer:
x=2 and y=-1
Step-by-step explanation:
set equations equal
X² + 2x +3
If the discriminent Δ = b²-4.a.c <0 , that means the roots (or the zero value) are nit REAL Number (they are imaginary or complex)
Δ = 2² - 4(1)3) = 4 - 12 = -8
since Δ = - 8 < 0 there are no real roots
