A particular concentration of a chemical found in polluted water has been lethal to 70% of the fish that are exposed to the concentration for 24 hours. Fifteen fish are placed in a tank containing this concentration of chemical in water.

A) Find the expected number of fish that survive in the tank. Calculate the standard deviation of the number of fish that survive in the tank. Round the standard deviation to one decimal places.

B) Find the probability that the number of fish that survive is within one standard deviation of the mean.