HI to all the people on here! Found this forum on here while looking for some help!! Hope someone on here can help me out!

here is the question:

Sunny's Restaurant boasts that average price of a full-course dinner is $25. It is known that the standard deviation of dinner prices is $10.20.

a. Assuming we know nothing about the shape of the data set, at least what percentage of time will the cost of a full-course meal be between $7.15 and $42.85?

b. Assuming we can verify that the data set is approximately normally distributed, what percentage of time will the cost of a full-course meal be greater $14.80?

c. Assuming we can verify that the data set is approximately normally distributed, 68% of the dinner prices will be within what range?

Thanks