ANSWER IT IF YOU CAN..IT IS A CHALLENGE.. instalment.
5 Rajiv Bhardwaj has a recurring deposit account in a bank of 3600 per month. If the
bank pays simple interest of 7% p.a. and he gets 15450 as maturity amount, find the
total time for which the account was held.
Answers
Step-by-step explanation:
Amount deposited per month (P) = ₹ 600
Rate of interest = 7% p.a.
Amount of maturity = ₹ 15450
Consider n months as the period
We know that
Total principal for one month = 600 × n (n + 1)/ 2
By further calculation
= 600 (n2 + n)/ 2
= 300 (n2 + n)
Here Interest = PRT/ 100
Substituting the values
= (300 (n2 + 1) × 7 × 1)/ (100 × 12)
= 7/4 (n2 + n)
Amount of maturity = 600n + 7/4 (n2 + n)
Substituting the values
600n + 7/4 (n2 + n) = 15450
By further calculation
2400 + 7n2 + 7n = 61800
7n2 + 2407n – 61800 = 0
We can write it as
7n2 – 168n + 2575n – 61800 = 0
7n (n – 24) + 2575 (n – 24) = 0
(n – 4) (7n + 2575) = 0
Here n – 24 = 0 where n = 24
Similarly
7n + 2575 = 0
Where 7n = -2575
n = -2575/7 which is not possible as it is negative
Period (n) = 24 months or 2 years
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