A set of data has a mean of 75 and

A set of data has a mean of 75 and a standard deviation of 5. You know nothing else about the size of the data set or the shape of the data distribution.
a. What can you say about the proportion of measurements that fall between 60 and 90?
b. What can you say about the proportion of measurements that fall between 65 and 85?
c. What can you say about the proportion of measurements that are less than 65?