A sequence of odd numbers is grouped the following way;

How many numbers are there in the th group?

(this seemed straightforward enough. By observation; )

How many numbers are there from the st group to the th group?

(this is where everything goes downhill for me, would be great to get some help...)

What is the first number in the th group?

What is the sum of all the numbers in the th group?

What is the sum of all the numbers in the th group?

Once again, any help appreciated.