posted by waqas .
3.The lifespan of 300 Giant turtles is found to follow a Normal distribution ~ N(70,144).
(a)What is the standard error for this sample’s mean? (b) What is the probability of a turtle living more than 85 years?
(c)What is the probability of a turtle living between 60 and 65 years?
(d)Find the 98% confidence interval for the mean lifetime.
(e) Below what age do the shortest lived 15% of turtles die?
SEm = SD/√n
Z = (score-mean)/SD or SEm, depending on whether you are talking about a distribution of individual scores or means respectively.
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions related to the Z scores.