Current research indicates that the distribution of the life expectancies of a certain protozoan is normal with a mean of 46 days and a standard deviation of 10.5 days. Find the probability that a simple random sample of 49 protozoa will have a mean life expectancy of 47 or more days.
a) 0.7475
b) 0.5379
c) 0.4525
d) 0.2525
e) 0.5050
f) None of the above