Question

A pediatrician finds that about 15% of the infants now injected with the MMR vaccine, as required by law in many states, develop some form of minor reactions. If the doctor intends to inject 400 infants during the year with this vaccine:
a) About how many can be expected (µ=np) to develop any form of a reaction.
b) Find the standard deviation.
c) What is the probability that out of the 400 infants, exactly 25 will develop a reaction? Write your answer as a decimal.