Answer:
203 minutes
Step-by-step explanation:
This can be expressed as an arithmetic sequence, that is
20, 23, 26, 29,...
With first term a = 20 and common difference d = 3
The sum to n terms of an arithmetic sequence is
[tex]S_{n}[/tex] = [tex]\frac{n}{2}[/tex] [ 2a + (n - 1)d ], hence
[tex]S_{7}[/tex] = [tex]\frac{7}{2}[/tex] [ (2 × 20) + (6 × 3) ]
= 3.5 ( 40 + 18) = 3.5 × 58 = 203
