Question 33722
the equation for interest is:
Y = A(1+r)^t
where y is the final amount
where a is the initial amount
where r is the rate
where t is the time in years
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1) Bud charged a $588 couch on his card from bank B. If he pays for the couch in a year, how much interest will he pay?

y = 588(1.15)^1
y = 676.2
676.2-588=88.2
the interest would be $88.20
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2) Maria charged $29 and $84 on her card from bank D. If she plans to pay her balance in three months, what is the total she must pay?

y = (29+84)(1.18)^(1/4)
y = (113)(1.18)^(1/4)
y = 117.77
117.77-113 = 4.77
the interest would be $4.77

-Attention-
these interests are not included with the annual fee for the card