Simple interest

Question

A sum of rs. 10 is lent to be returned in 11 monthly installments of rs.1 each , interest being simple. the rate of interest is?

Answer 1

Total amount to be paid back = 11₹, which should be equal to Principal + Simple Interest.
Here Principal = 10₹, so simple interest = 1₹.
Simple Interest = (principal x rate of interest x time period)/100.
So rate of interest = (S.I. x 100)/(principal x timeperiod).
Rate of interest = (1 x 100)/(10 x 11) = 10/11= 0.91% per month.

Comments

Sir , i had also solved lyk this bt this z nt a correct ans..answer is 21 9/11 %

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I don't think my procedure is wrong, however if we have to calculate rate of interest per annum then by changing time from months( = 11) to years (= 11/12), rate of interest will be 120/11 = 10.91% PER ANNUM.

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120/11   per annum

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I guess for installment they took time period as t/2.