.85x=10.2
your answer is x = 12
Answer:
The confidence limits for the proportion that plan to vote for the Democratic incumbent are 0.725 and 0.775.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of
, and a confidence level of
, we have the following confidence interval of proportions.

In which
z is the zscore that has a pvalue of
.
Of the 500 surveyed, 350 said they were going to vote for the Democratic incumbent.
This means that 
80% confidence level
So
, z is the value of Z that has a pvalue of
, so
.
The lower limit of this interval is:

The upper limit of this interval is:

The confidence limits for the proportion that plan to vote for the Democratic incumbent are 0.725 and 0.775.
The amount of hours you worked would be 7.5, you divide 600 by 80.