You bike 3 miles the first day of your training, 3.3 miles the second day, 3.9 miles the third day, and 5.1 miles the fourth day. If you continue this pattern, how many miles do you bike the seventh day?

The answer to your question is 21.9 mi

Step-by-step explanation:

Data

1st day = 3 mi

2nd day = 3.3 mi

3rd day = 3.9 mi

4rd day = 5.1 mi

7fh day = ?

Process

1.- Calculate the pattern

Day            1           2           3         4        5          6         7

MIles          3          3.3         3.9     5.1    7.5       12.3     21.9

Gradient          0.3         0.6       1.2    2.4    4.8      9.6

We notice that the gradient is duplicating so the miles that I bike the seventh day are 21.9.