in a certain city, men have heights distributed normally with mean 170 cm and standard deviation 10 cm.
i) find the probability that the mean height of 3 randomly selected men is greater than 178 cm.
ii) find the probability that the mean height of a random sample of 20 men differs from the population mean height by more than 10 cm.
i need some help with the second part.
the distribution i formed is X~ N(170, (10^2)/20)
then i proceeded to standardize by doing the following