Answer:
A sample of 179 is needed.
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 = 1.44.
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.
A previous study found that for an average family the variance is 1.69 gallon?
This means that 
If they are using a 85% level of confidence, how large of a sample is required to estimate the mean usage of water?
A sample of n is needed, and n is found for M = 0.14. So






Rounding up
A sample of 179 is needed.
Answer: 350
Step-by-step explanation:
Let the cheeseburger be represented by a.
Since there were 51 fewer cheeseburgers sold than hamburgers. This means that hamburgers will be:
= a + 51.
Since the local hamburger shop sold a combined total of 649 hamburgers and cheeseburgers. This will be:
a + a + 51 = 649
2a + 51 = 649
2a = 649 - 51
2a = 598
a = 598/2
a = 299
299 cheeseburger were sold
Therefore, the number of hamburger sold will be:
= 649 - 299
= 350
Is gonna be the family plan please give brainlist and help me report the comment on top is a page virus
The correct answer should be :
Option 3 : 
Hope this helps,
Davinia.