SOLUTION: kamal buys a washing machine for rs10000.he pays rs2000 in cash and agrees to pay the balance in installment of rs500 plus 10% interest on the unpaid amount. find the total amount
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Question 919949: kamal buys a washing machine for rs10000.he pays rs2000 in cash and agrees to pay the balance in installment of rs500 plus 10% interest on the unpaid amount. find the total amount paid for the washing machine Answer by Theo(13342) (Show Source):
You can put this solution on YOUR website! since kamal needs to pay off 8000 rs in equal increments of 500 rs each, kamal will need to make 16 payments because 16 * 500 = 8000.
every time kamal makes a payment of 500 rs, he also need to pay 10% of the remaining balance.
for example:
kamal owes 8000 rs.
he makes a payment of 500 rs.
there is 7500 rs left in the loan so kamal pays 10% of that which is equal to 750 rs.
kamal owes 7500 rs.
he makes a payment of 500 rs.
there is 7000 rs left in the loan so kamal pays 10% of that which is 700 rs.
each time kamal makes a payment, kamal needs to pay 500 rs plus 10% of the unpaid balance which is 50 rs less each time.
that makes this an arithmetic series type of problem where A1 = 750 and d = -50 and n = 16.
the formula for the sum of an arithmetic series is:
Sn = n * (A1 + An) / 2
in this problem, n = 16 and A1 = 750 and An = 0 so the formula becomes:
Sn = 16 * (750 + 0) / 2 which becomes:
Sn = 8 * 750 which becomes:
Sn = 6000
kamal will have to pay 8000 in equal installments of 500 each plus additional 6000 in interest for a total of 14,000 rs.
the individual calculations are shown below for you to see how this worked out.
one can argue that the interest had to be paid on the unpaid balance before the payment was made which would change the problem slightly.
my interpretation is that the interest had to be made on the unpaid balance after the payment was made and that is what my calculations were based on.
the alternate interpretation would yield the following calculations.
Sn = 16 * (800 + 50) / 2 = 8 * 850 = 6800.
that's an addition 800 in interest that would would have to be paid.
