A consumer charges a $2,530.16 purchase on their credit card. the card has a daily interest rate of 0.042%. if the consumer pays off the balance at the end of 30 days, how much more in interest will they pay for the purchase?

a. $0.32

b. $3.19

c. $31.88

d. $318.78

Amount after interest = original amount x (interest rate) ^ (time)

Amount after interest = 2,530.16 x 1.00042³⁰

Amount = $2562.23

Interest = 2,562.23 - 2,530.16

= $32.07

The answer is C.

The equation that we need to use to answer the question above is,

I = P x ((1+r) ^t) - P

where P is the principal amount, r is the interest rate (in its decimal equivalent) and t is time. Substituting the known values from the given,

I = ($2,530.16) x ((1 + 0.042/100) ^30) - $2,530.16

I = $32

The nearest answer should be letter C.