The set given is <span>{1, 3, 5, 7, 9, 11, 13} and is asked in the problem to determine the number of integers that are defined as the difference of the two numbers.
In this question, 10 people average running distance is 2.7miles. Then the sum of their running distance would be: 10 people * 2.7 miles/people= 27 miles.
The group then divided into 2, 4 people with 3 miles average and 6 people with unknown average. Since the people are same like the 10 people group, their total running distance would be the same. The calculation would be:
total distance = group1 * average1 + group2 * average2 27 miles= 4 people * 3 miles/people + 6 people* average2 6 people * average2 = 27 miles -12 miles = 15 miles average2= 15 miles/6people= 2.5 miles/people