Mr.Sarojini deposits Rs.1600 per month  in cumulative account at 9% per annum s.i, .If she gets Rs.65592 at the time of maturity, find the total time for which account was held.
Answer must be 3years.

Asked by sreenivasanmaralapadu | 10th Jul, 2015, 07:58: PM

Expert Answer:

G i v e n space t h a t space m o n t h l y space d e p o s i t equals R s.1600 I n t e r e s t equals 9 % M a t u r i t y space a m o u n t equals R s.65592 L e t space n space b e space t h e space n u m b e r space o f space m o n t h s. N equals fraction numerator n open parentheses n plus 1 close parentheses over denominator 2 cross times 12 end fraction W e space k n o w space t h a t space t h e space m a t u r i t y space a m o u n t comma A m o u n t equals P n plus fraction numerator P N R over denominator 100 end fraction rightwards double arrow 65592 equals 1600 cross times n plus fraction numerator 1600 cross times n open parentheses n plus 1 close parentheses cross times 9 over denominator 2 cross times 12 cross times 100 end fraction rightwards double arrow 65592 equals 1600 cross times n plus 6 n squared plus 6 n rightwards double arrow 6 n squared plus 1606 n minus 65592 equals 0 rightwards double arrow 6 n squared plus 1822 n minus 36 n minus 65592 equals 0 rightwards double arrow n open parentheses 6 n plus 1822 close parentheses minus 36 open parentheses 6 n plus 1822 close parentheses equals 0 rightwards double arrow open parentheses n minus 36 close parentheses open parentheses 6 n plus 1822 close parentheses equals 0 rightwards double arrow n minus 36 equals 0 space o r space 6 n plus 1822 equals 0 rightwards double arrow n equals 36 space o r space n equals fraction numerator negative 1822 over denominator 6 end fraction A s space n space c a n n o t space b e space n e g a t i v e comma space n equals 36 space m o n t h s T h a t space i s space n equals 3 space y e a r s.

Answered by Vimala Ramamurthy | 11th Jul, 2015, 12:25: PM