Amy: x skirts
Betty: 2x skirts
Carol: (2x) + 7 skirts
If Amy has 18 less than Carol, than Carol's equation minus 18 equals Amy's equation:
[(2x) + 7] - 18 = x
+18 +18
(2x) + 7 = x + 18
- 7 -7
2x = x + 11
-x -x
x = 11
Input the solution for x into the girls equation to double check.
Amy: 11
Betty: 2(x)
2(11)
=22
Carol: (2x) + 7
22 + 7
=29
Does Amy have 18 less than Carol?
Carol - Amy = 18
29 - 11 = 18
18 = 18
the problem is solved
Answer:
So the answer for this case would be n=22547 rounded up to the nearest integer
Step-by-step explanation:
Let's define some notation
represent the sample mean
population mean (variable of interest)
represent the population standard deviation
n represent the sample size
represent the margin of error desire
The margin of error is given by this formula:
(a)
And on this case we have that ME =+1 and we are interested in order to find the value of n, if we solve n from equation (a) we got:
(b)
The critical value for 99% of confidence interval now can be founded using the normal distribution. The significance would be
and the critical value
, replacing into formula (b) we got:
So the answer for this case would be n=22547 rounded up to the nearest integer
I think it’s 390. I hope I’m not too late :V