Answer:
The 95% confidence interval  for the true proportion of mice that will test positive under similar conditions is (0.5291, 0.6429).
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of 
, and a confidence interval 
, we have the following confidence interval of proportions.

In which
Z is the zscore that has a pvalue of 
.
For this problem, we have that:
In a collection of experiments under the same conditions, 44 of 75 mice test positive for lymphadenopathy. This means that 
 and 
.
Compute a 95% confidence interval for the true proportion of mice that will test positive under similar conditions.
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 95% confidence interval  for the true proportion of mice that will test positive under similar conditions is (0.5291, 0.6429).