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:
B? I believe? sorry if it's wrong
Step-by-step explanation:

The summation symbol means we use the variable i in the equation from the given range. In this case, we are given with the equation 3 i - 15 and i ranges from 2 to 7. The summation using simply the calculator is equal to -9. The answer to this problem is -9.
The probability of Joey being first is 1/12. If that happens the probability of Chloe going next is 1/11. Then the probability of zoe being picked next would be 1/10. Then if you multiply all the fractions I gave you you would get 1/1320 which is A. So A. Is your answer!! Hope this helps you out!!