Answer:
We can solve this problem by using the combination formula, which is:
nCr = n! / (r! * (n - r)!)
where n is the total number of items (people in this case) and r is the number of items we want to select (the group size in this case).
To choose a pair of girls from the 7 girls in the group, we can use the combination formula as follows:
C(7, 2) = 7! / (2! * (7 - 2)!) = 21
Therefore, there are 21 ways to choose a pair of girls from the group.
Similarly, to choose a pair of boys from the 10 boys in the group, we can use the combination formula as follows:
C(10, 2) = 10! / (2! * (10 - 2)!) = 45
Therefore, there are 45 ways to choose a pair of boys from the group.
Since we want to choose a pair of the same-sex people, we can add the number of ways to choose a pair of girls to the number of ways to choose a pair of boys:
21 + 45 = 66
Therefore, there are 66 ways to choose a pair of the same-sex people from the group of 17 people.