Using the combination formula, it is found that:
1. A. 7 combinations are possible.
B. 21 combinations are possible.
C. 1 combination is possible.
2. There are 245 ways to group them.
<h3>What is the combination formula?</h3> is the number of different combinations of x objects from a set of n elements, given by:
Exercise 1, item a:
One letter from a set of 7, hence:
7 combinations are possible.
Item b:
Two letters from a set of 7, hence:
21 combinations are possible.
Item c:
7 letters from a set of 7, hence:
1 combination is possible.
Question 2:
Three singers are taken from a set of 7, and four dances from a set of 10, hence:
There are 245 ways to group them.
More can be learned about the combination formula at brainly.com/question/25821700