can you please help me with these? thanks in advance

Solve the problem below- Present your complete solution using this 5-point rubrics: 5 = complete and correct solution, 3-4 = presented underlying principles but did not get the correct answer, 1-2 = given data were presented but no underlying principles presented. PROBLEM: Find the probability that a normally distributed random variable will fall within these ranges: (a) one standard deviation of its mean (b) two standard deviation of its mean