Answer: has no equal sign
The answer to this question is 0.004
I am pretty sure it is 120 or 30
Answer: 68
Step-by-step explanation:
As per given , we have
Population standard deviation : 
Critical value for 90% confidence interval =
Margin of error : E= 0.8 milligrams
The formula to find the sample size is given by :-

i.e. 

Hence, the limnologist must analyze 68 samples.
I would answer this but I am not sure