Fisherman catching some yummy fish

• March 25th 2012, 08:04 PM
gigsaw
Fisherman catching some yummy fish
What formula do you use? How do I solve this?

A survey of 250 lobster fishermen found that they catch an average of 32.0 pounds of lobster per day with a standard deviation of 4.0 pounds. If a random sample of 36 lobster fishermen is selected, what is the probability that their average catch is less than 31.5 pounds? Assume the distribution of the weights of lobster is normal.
• March 25th 2012, 08:46 PM
pickslides
Re: Fisherman catching some yummy fish
Try $P(\bar{X} <31.5) = P\left(Z< \frac{31.5-32}{\frac{4}{\sqrt{250}}} \right)$
• March 25th 2012, 10:11 PM
biffboy
Re: Fisherman catching some yummy fish
For samples of 36 the standard deviation of the means is 4/root36=4/6.