A bank pays interest to its customers on the last day of the year. The interest paid to a customer
is calculated as 10% of the average monthly balance maintained by the customer. John is a
customer at the bank. On the last day, when the interest was accumulated into his account, his
bank balance doubled to $1710. What is the average monthly balance maintained by John in his
account during the year? Choose the correct answer.
A) 2840 B) 5680 C) 6840 D) 8550 E) 28400
Soln:-   Bank balance is doubled with accumulation of interest to 1710..   this means INTEREST is   1710/2= 
<gadget id="calculator">  1710/2</gadget>
<output>855</output>
855 for entire year..   although since interest is 10% of avg MONthly balance, it becomes 8550..   ANSWER:8550
<result>D</result>
A bank pays interest to its customers on the last day of the year. The interest paid to a customer
is calculated as 10% of the average monthly balance maintained by the customer. John is a
customer at the bank. On the last day, when the interest was accumulated into his account, his
bank balance doubled to $1710. What is the average monthly balance maintained by John in his
account during the year?