Which function is represented by the graph?

a) f(x) = –|x| + 4
b) f(x) = –|x| – 4
c) f(x) = –|x + 4|
d) f(x) = –|x – 4|

answer: $53750

steps:

list the principal and interest after the n-th year:

n       principal   simple interest

1     12500     375

2     25000     750

3     37500     1125

4     50000     1500

sum: $50000     $3750

total at end of year 4: $53750