Steps toward getting a useful answer:

• Start by reading the course materials, if any.
• Try to get started with it.
• If you run into a roadblock, ask the instructor about it.
• If (s)he's not able to explain clearly enough to help, post here what you've done so far and ask a specific question on how to proceed.

It will be ineffective to just ask people to do your homework for you. But the primary reason for the ineffectiveness isn't that people here aren't willing to help. It's that us doing your homework is ineffective at helping you to master the subject matter. Since we're generally aware of that fact, and since this site is geared toward helping people in their quest for knowledge (as opposed to their need to turn in assignments on time), we're often hesitant to just provide the answer when there's little apparent effort. That's just not what we're all about here.

In the case of your problem, I would do this: I would create four variables. One to hold the lowest value entered. One to hold the highest value entered. One to hold the tally of all values entered. And one to keep track of how many values have been entered. I would initially set all the variables to hold 'undef'. Then I would start a loop. I would query for input. I would test for a blank line. Then I would chomp, test for min-ness and max-ness (setting a new min or max if necessary), I would add the input value to the tally, and I would increment the sample count. If I wanted to play it safe I would also reject any input that was non-numeric. After the loop ends I would take care of the math and print the output. Often if you think through the steps, the code becomes easy.