Answer:
21.
Step-by-step explanation:
Since there were five teams entered in a competition, and each team consisted of either only boys or only girls, with the number of team members being 9, 15, 17, 19 and 21 members, if after one team of girls had been knocked out of the competition, the number of girls still competing was three times the number of boys, to determine how many girls were in the team that was eliminated, the following calculation must be performed:
9 + 15 + 17 + 19 = 60/4 = 15
9 + 15 + 17 + 21 = 62/4 = 15.5
9 + 15 + 19 + 21 = 64/4 = 16
9 + 17 + 19 + 21 = 66/4 = 16.5
15 + 17 + 19 + 21 = 72/4 = 18
Thus, since 15 x 3 equals 45, and 45 plus 15 equals 60, the number of girls on the team that was eliminated was 21.
