Step-by-step explanation:
In the first week of his running plan,the number of miles covered = 5 miles
Weekly mileage will increase by 3.5 miles every week.
At the end of second week, the number of miles covered = 5 + 3.5 = 8.5
At the end of third week, the number of miles covered = 8.5 + 3.5 = 12
The series is 5, 8.5, 12, ...
Consider this as an AP, where a = 5, d = 3.5
By formula,
[tex]a_{n} = a + (n-1)d[/tex]
Substituting the values in the above equation, we get
[tex]a_{11} = 5 + (10-1) 3.5[/tex]
= 5 +(9)3.5
= 5 + 31.5
=36.5 miles.
Gavin would be expected to run during 36.5 miles during his 11th week of the training plan