Answer:
The 80% confidence interval for the mean usage of water is between 18.4 and 18.6 gallons per day.
Step-by-step explanation:
We have that to find our 
level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Ztable as such z has a pvalue of 
.
So it is z with a pvalue of 
, so 
Now, find the margin of error M as such
In which 
is the standard deviation of the population and n is the size of the sample.
The lower end of the interval is the sample mean subtracted by M. So it is 18.5 - 0.1 = 18.4 gallons per day.
The upper end of the interval is the sample mean added to M. So it is 18.5 + 0.1 = 18.6 gallons per day.
The 80% confidence interval for the mean usage of water is between 18.4 and 18.6 gallons per day.
Answer:
Julie would have 800 pens
Step-by-step explanation:
You would convert the fraction to a decimal which would be 0.8 and then you would multiply that by 1000 which would be 800. So Julie would have 800 pens.
4/5 = 8/10 = 0.8
0.8 * 1000 = 800
The answer is going to be a fraction...which is 75/1000, otherwise known as 1/40
I believe it's 9x2-12x+4 but I'm not quite sure cause we haven't yet gone over this in class.
My friend also believes it is this (she's in a higher level math grade than me). I'm so sorry this isn't more helpful.
Step-by-step explanation:
