Higher interest rates could be caused by

A. an increase in the money supply
B a decrease in the money supply
C no change in the money supply
D a decrease in the demand for money
E no change in the demand for money

Iam pretty sure it is c.

You're asking in the ap section, so i'll give the ap calculus-style answer. alternatively, you can find the vertex of the parabola and use the "y"-coordinate as the answer.

the maximum height can occur at a critical number, that is, a number  such that  .

the derivative of  can be calculated as follows:



find a value of  that is a zero of the derivative:


this is parabola that is opening downward; we can assume there is a maximum at  .

to find that maximum, calculate  .

At 8.5% i am making after one year 1,500   +  1,500 x 0.08 = $1,620

my credit card cost 1,600 + 1,600 x 0.19 = $1,904


total balance =  interest  (negative)  of credit card + interest earn (positive)

that is  -304 + 120 = -$181