Sinα=cos(90-α) this is an identity which you need to know...
in this case:
sin49°=cos41°
The answer is B.
This is because A is incorrect, Zach number of minutes didnt increase by an equal factor every month.
C and D are incorrect, Victoria's methods aren't exponential, but Zach's are.
So that leaves the only reasonable answer which is B.
Answer:
19.9 miles
Step-by-step explanation:
In this problem we have:
is the distance travelled during the 1st day
is the distance travelled during the 2nd day
is the distance travelled during the 3rd day
is the distance travelled during the 4th day
We notice that the difference between the distance travelled on the (n+1)-th day and the distance travelled on the n-th day doubles every day. In fact:

Which can be rewritten using the general formula:

This means that

By applying this formula recursively, we can find the 7th term, which is the distance travelled on the 7th day:

So, the distance travelled on the 7th day is 19.9 miles.