Answer:
The 80% confidence interval for the population mean is between 28.32 characters and 31.68 characters.
Step-by-step explanation:
We have the standard deviation for the population, so we can use the normal distribution. If we had the standard deviation for the sample, we would have to use the t-distribution.
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 30 - 1.68 = 28.32 characters.
The upper end of the interval is the sample mean added to M. So it is 30 + 1.68 = 31.68 characters.
The 80% confidence interval for the population mean is between 28.32 characters and 31.68 characters.
Answer:
A person needs to write each month 1.17 checks for the two banks to charge the same amounts in fees.
Step-by-step explanation:
You can write an equation in which the amount charged by bank a is equal to the amount charged by bank b. The amount bank a charges is 6 plus 0.10 for the number of checks written and the amount bank b charges is 5.20 for the number of checks written.
6+0.10x=5.20x, where x is the number of checks written
Now, you can solve for x to find the number of checks written where the two banks charge the same amounts in fees:
6=5.20x-0.10x
6=5.10x
x=6/5.10
x=1.17
According to this, the answer is that a person needs to write each month 1.17 checks for the two banks to charge the same amounts in fees.
Answer: The unit rate is 16 miles per gallon
Step-by-step explanation:
464 miles for 29 gallons
? miles for 1 gallon
29x = 464
Divide both sides by 29
x = 16
Answer:
B C E
Step-by-step explanation:
Read the question
