Answer:
x3 + 4
Step-by-step explanation:
Scince Bill's friends amount of miles is unkown its x, and times it by three since it says times, and then add 4 since it says more than! Hope this helps! There is a really good website called Khan Academy and it explains everything! Just search in google your topic and say khan academy at the end and you will get practices and videos! Good luck!
The main rules that we use here are :
i)

for nonnegative values a and b.
ii)

.
Thus, first 'decompose' the numbers in the radicals into prime factors:

.
By rule (i) we write:

.
We can collect these terms as follows:

, and by rule (ii) we have:

Answer:

.
Answer:
The 80% confidence interval for the mean number of toys purchased each year is between 7.5 and 7.7 toys.
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
.
That is z with a pvalue of
, so Z = 1.28.
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 7.6 - 0.1 = 7.5
The upper end of the interval is the sample mean added to M. So it is 7.6 + 0.1 = 7.7
The 80% confidence interval for the mean number of toys purchased each year is between 7.5 and 7.7 toys.
Answer:
4.5
Step-by-step explanation: