Hypothesis test problem ?

Hi all,
I want to solve the following problem. But I don't have understand exactly what I have to do.
Could you help me please ?

A news feed is tested to see if it increases the length of a lizard.
23 lizards eat 12.5 kg of food for two weeks. Once finished the experiment
count the length of the lizards and observe that the average length is x'= 14.3cm
with a standard deviation s = 1.3 cm.
The experience about lizards kind before the food showed that the lizards average length was μ=14.1 and σ = 1.
(in a particular age),

A)What is the probability of x' as accurate estimator of μ?
What is the accuracy in practice?
Is it the estimator consistent (as expected from theory)?

B) How big must be the experiment in order to be sure with probability 0.95 that
estimators error will not be over the 0.2cm ?

Thanks a lot for your time