Answer:
The 98% confidence interval for the mean purchases of all customers is ($37.40, $61.74).
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 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 mean subtracted by M. So it is 49.57 - 12.17 = $37.40.
The upper end of the interval is the mean added to M. So it is 49.57 + 12.17 = $61.74.
The 98% confidence interval for the mean purchases of all customers is ($37.40, $61.74).
Multiply all the numbers by 2 first, so 12 yards 18 ft 8 in. After that, you simplify. There are three feet in a yard, so in eighteen feet there are 6 yards. That makes 18 yards and 8 in
Answer:
C
Step-by-step explanation:
Using the rule of radicals
×
⇔ 
Simplifying each radical before combining them.

=
=
×
= 3
-----------------------------------------------------------------------------

= 
=
×
= 5
---------------------------------------------------------------------------
Hence
2(3
) - 3(5
= 6
- 15
= - 9
→ C