Answer:
The 90% confidence interval for the average monthly residential water usage for all households in this city is between 4401.3 gallons and 4598.7 gallons.
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 4500 - 98.7 = 4401.3 gallons
The upper end of the interval is the sample mean added to M. So it is 4500 + 98.7 = 4598.7 gallons
The 90% confidence interval for the average monthly residential water usage for all households in this city is between 4401.3 gallons and 4598.7 gallons.
4/5-1/8=0.675 and that’s the answer
1. 12 mph, 24 miles
2. m=4, y=22
3.15/1, $1500
4. x=30 y=60, k cheaper, j cheaper
Answer:
x = 3 and x = 
Step-by-step explanation:
(a)
2(5x - 3) = 24 ( divide both sides by 2 )
5x - 3 = 12 ( add 3 to both sides )
5x = 15 ( divide both sides by 5 )
x = 3
(b)
5(2x + 1) = 50 ( divide both sides by 5 )
2x + 1 = 10 ( subtract 1 from both sides )
2x = 9 ( divide both sides by 2 )
x = 