Assume that each month the average Canadian household generates an average of 13kg of newspaper for garbage or recycling with a standard deviation of 1kg. What is the probability that a randomly selected household generates between 12 and 15 kg of newspaper per month?

Question

Assume that each month the average Canadian household generates an average of 13kg of newspaper for garbage or recycling with a standard deviation of 1kg. What is the probability that a randomly selected household generates between 12 and 15 kg of newspaper per month?
A) 23.08%
b) 34.13%
c) 47.72%
d) 49.87%
e) 81.85%

By using z-scores I managed the answer of 49.87. Somehow it appears that other classmates consistently attained 81.85, how is this so?

bobpursley · Answer

http://davidmlane.com/hyperstat/z_table.html Your classmates are right.

Anonymous · Answer

However, on an exam I will not have a computed normal distributions. How do you manage this manually?

Anonymous · Answer

Never-mind. Question answered.Thank you.