Question

Simone was given a task at work that she did for several days.

On the first day, she completed the task in 60 minutes.
On the second day, she completed the task in 58.5 minutes.
On the third day, she completed the task in 57 minutes.
On the fourth day, she completed the task in 55.5 minutes.
The number of minutes it took Simone to complete the task continued to follow the same pattern.
Which function represents the number of minutes it took Simone to complete the task on the
n
th
𝑛
th
day?

Answer 1

The times form an arithmetic sequence with first term 60 and common difference -1.5. So the nth-day time is

f(n) = 60 + (n−1)(−1.5) = 60 − 1.5(n−1) = 61.5 − 1.5n.