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
Answer:
X=3
Step-by-step explanation:
Answer:
the first 6⅔
Step-by-step explanation:
in the image
Answer:
A
Step-by-step explanation:
(x-4)^2 = x^2 -4x -4x + (-4)*(-4)
= x^2-8x+16 as required