Answer:
a)
And we can conclude that we are 95% confident that the true mean of Co2 level is between 608.29 and 700.03 ppm
b)
Step-by-step explanation:
Part a
The confidence interval for the mean is given by the following formula:
(1)
In order to calculate the critical value we need to find first the degrees of freedom, given by:
Since the Confidence is 0.95 or 95%, the value of and , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.025,51)".And we see that
Replacing we got:
And we can conclude that we are 95% confident that the true mean of Co2 level is between 608.29 and 700.03 ppm
Part b
The margin of error is given by :
(a)
The desired margin of error is ME =50/2=25 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 95% of confidence interval now can be founded using the normal distribution. And in excel we can use this formla to find it:"=-NORM.INV(0.025;0;1)", and we got , and we use an estimator of the population variance the value of 175 replacing into formula (b) we got:
Answer:
9x-4
Step-by-step explanation:
add 5x and 4x
9x-3-1
subtract 1 from -3
9x-4
0.765 (100) + .06 (.0765 x 100)
76.5 + .06 (76.5)
76.5 + 4.59 = 81.09 Chris will pay $81.09
A better way ( if you don't care to know the tax just the bottom line of what it will cost) would be to do:
0.765x x 1.06 = 76.5 x 1.06 = $81.09 too.
Why the 1 in front of the .06? The one includes the price of the coat so you don't have to add the tax on after.
Think about it like this. When you buy something you pay (even with an employee
discount) for all of it (100%) + the tax (in this case, it's 6%) So you pay 106% of the cost of the item. 106% = 1.06
If you can give me more information on this I could help you a bit more respond.