30 Patients treated for the same illness were given a new treatment. They were then asked to evaluate whether 5 symptoms H,L,P,T,V were made better or worse by the new treatment.

For each symptom patients used one of the five ratings:
2: much better
1: somewhat better
0: same
-1:somewhat worse
-2:much worse

Symptom:
H , Sum of 30 ratings of H: 12 , Standard Deviation of 30 ratings of H: 1.4
L , Sum of 30 ratings of L: 35 , Standard Deviation of 30 ratings of L: 0.69
P , Sum of 30 ratings of P: -33 , Standard Deviation of 30 ratings of P: 0.79
T , Sum of 30 ratings of T: -26 , Standard Deviation of 30 ratings pf T: 0.43
V , Sum of 30 ratings of V: 2 , Standard Deviation of 30 ratings of V: 0.89

Problem:
For the symptom whose arithmetic mean rating was closest to 0, approximately what was the arithmetic mean rating?


I know the symptom T's arithmetic mean rating was closest to 0,
But I don't know how to calculate the mean with the information given
the answer is: 0.067

Please help! thankyou

anyone?

The sample mean is equal to the sum divided by the number of observations. Finding the symptom whose arithmetic mean is closest to 0 is equivalent to finding the symptom whose sum is closest to 0 (note this isn't true in general, but only when the number of observations for each group is the same). Then, for 30 obs, you divide the sum by 30. In this case, V has the arithmetic mean closest to 0, since it's sum is closest to 0. Divide that number by the number of obs (30) and you get the desired answer.

The standard deviations given are either red herrings or are meant to be used on a different problem with the same given information.