Answer:
609
Step-by-step explanation:
Standard deviation = 
= $30
Margin of error = E = $2
Confidence level = 90%
Since the distribution is said to be normal, we will use z scores to solve this problem.
The z score for 90% confidence level = z = 1.645
Sample size= n = ?
The formula to calculate the margin of error is:
Using the values in above equation, we get:
This means, the minimum number of observations required is 609
Just plug stuff in
(0, 32)
(100, 212)
(-20, -4)
(10, 50)
Answer: About 804.25
Step-by-step explanation:
Do the inverse of the circumference formula and then take the radius and put it into the formula for the area of a circle
Because the coefficient of x^2 is -1, we know that a will be -1. Knowing that the coefficient of x is -4, we can calculate that p=2. Thus, we have -1(x+2)^2+q is our equation. This is equal to -x^2-4x-4+q. As the constant term must be 2, we can then see that q is 6.
As such, we have -1(x+2)^2+6=0 as our factorization.
To solve this equation, we can use the quadratic formula. Plugging in values, we have:
which is equal to: (when the fraction is simplified)
Answer:a=2.1 :)
Step-by-step explanation:a+(-1.6)=-3.7
+1.6 +1.6
a=-2.1
