Rebecca is training for the swim team tryouts. She plans to swim an average (mean) of 5.5 miles a

week. So far, she has swum 2 miles the first week, 7 miles the second week, 6 miles the third week, 9

miles the fourth week, 5 miles the fifth week, and 3 miles the sixth week. How many miles must she

swim the seventh week, in order to reach her goal of averaging 5.5 miles per week?

Therefore she must swim = 6.5 miles the seventh week

Step-by-step explanation:

Given, Rebecca plans to swim an average of 5.5 miles per week.

So, she has swum 2 miles the first week, 7 miles the second week, 6 miles the third week, 9 miles the fourth week, 5 miles the fifth week and 3 miles the sixth week.

Total she has swum = (2+7+6+9+5+3) miles in six week.

=32 miles

To reach her goal she has to swim = (5.5*7) miles = 38.5 miles at the end of seventh week.

Therefore she must swim = (38.5 - 32) miles = 6.5 miles the seventh week