Answer:
The 99% confidence interval for the true mean number of reproductions per hour for the bacteria is between 9.6 and 10.
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 the margin of error 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 sample mean subtracted by M. So it is 9.8 - 0.2 = 9.6 reproductions per hour.
The upper end of the interval is the sample mean added to M. So it is 9.8 + 0.2 = 10 reproductions per hour.
The 99% confidence interval for the true mean number of reproductions per hour for the bacteria is between 9.6 and 10.
The is a I think or it could be c I really don’t know sorry I try’s
So, with 12 check outs and 4 stays over you will have to clean up 16 rooms ( I assume that the hotel has the habit of cleaning up the room even if people stay overnight)
so the time between 9 am and 3 pm is 4 hours, that is 4*60=240 minutes.
This means it's 240/16=120/8=60/40=15, 15 minutes per room.
About the first part of the sentence: I assume that you can start washing the dishes alrady at 6:30 (dishes you used for preparation,etc) - so you can clean up from 6:30 till 9:30 - that is three hours!
