Answer: 8359
Step-by-step explanation:
The formula for sample size needed for interval estimate of population proportion :-

Given : The significance level : 
Critical value : 
Previous estimate of proportion : 
Margin of error : 
Now, the required sample size will be :-

Hence, the required sample size = 8359
7.9168 x 10^8
790000000 + 1680000 = 791680000
Answer:
The margin of error for a 90% confidence interval is 16.4
Step-by-step explanation:
We are given the following in the question:
Sample size, n = 25
Standard deviation = 50

Margin of error =

Putting the values, we get,

Thus, the margin of error for a 90% confidence interval is 16.4
Answer:
The drama club bought 35 t-shirt
Step-by-step explanation:
Let
t-shirt = x
Sweatshirt = y
Total cost = $795
They purchase 20 more tshirts than sweatshirts
x = y + 20
The equation is:
12x + 25y = 795
12(y + 20) + 25y = 795
12y + 240 + 25y = 795
37y = 795 - 240
37y = 555
y = 15
Substitute y = 15 into
x = y + 20
x = 15 + 20
x = 35
t-shirt = 35
Sweatshirt = 15
The drama club bought 35 t-shirt


etc.

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