Question

STATISTICS PLEASE HELP

Answer 1

Answer:

95

Step-by-step explanation:

If the mean is 400 and the standard deviation 12.5. It means that a range between 375 and 425 is the mean +- 2 standard deviations

400 - 12.5*2 = 375

400 + 12.5*2 = 425

Which means the probability is 95%

When you are looking for +- 1 deviation standard the probability is 68, and for +- 3 the probability is 99.7

There is a more complex explanation based on Z, but assuming you are only applying 68-95-99.7 rule this should be enough.