Answer:
Mean = 1.57
Variance=0.31
Step-by-step explanation:
To calculate the mean and the variance of the number of successful surgeries (X), we first have to enumerate the possible outcomes:
1) Both surgeries are successful (X=2).
2) Left knee unsuccessful and right knee successful (X=1).
3) Right knee unsuccessful and left knee successful (X=1).
4) Both surgeries are unsuccessful (X=0).
Then, the mean can be calculated as the expected value:
The variance can be calculated as:
600 + 300 + 150 + . . . is a geometric sequence with a = 600 and r = 1/2
Sn = a(1 - r^n)/(1 - r)
S5 = 600(1 - (1/2)^5)/(1 - 1/2) = 600(1 - 1/32)/(1/2) = 1,200(31/32) = 1,162.5
Answer:
x = 1 + i sqrt(7/2) or x = 1 - i sqrt(7/2)
Step-by-step explanation:
Solve for x:
2 x^2 - 4 x + 9 = 0
Divide both sides by 2:
x^2 - 2 x + 9/2 = 0
Subtract 9/2 from both sides:
x^2 - 2 x = -9/2
Add 1 to both sides:
x^2 - 2 x + 1 = -7/2
Write the left hand side as a square:
(x - 1)^2 = -7/2
Take the square root of both sides:
x - 1 = i sqrt(7/2) or x - 1 = -i sqrt(7/2)
Add 1 to both sides:
x = 1 + i sqrt(7/2) or x - 1 = -i sqrt(7/2)
Add 1 to both sides:
Answer: x = 1 + i sqrt(7/2) or x = 1 - i sqrt(7/2)
