abhinav purchases a track suit for rs 2400 cash or for rs 1000 cash down payments and two monthly instalment of rs 800 each find the rate of interest
Answers
Answer:
the rate of interest is 20%
Step-by-step explanation:
Cost Price at down payment = Rs 2400
if he made Rs 1000 down payment then remaining payment = 2400 - 1000
= Rs 1400
He will make payment of Rs 800 + 800 = Rs 1600 more
Interest paid = Rs 1600 - Rs 1400 = Rs 200
Interest paid on Amount Rs 1400
Rs 200 interest paid on Rs 1400 in two months
Simple interest Rate = r % per annum
200 = 1400 * r * (2/12)/100
=> r = 600/7
=> r = 85.7% per annum
7.15 % per month
if Compound interest r % per month
Then interest for 1st month
= 1400 * r * 1/100 =
= 14r
in 1st installment Principle paid = 800 - 14r & interest paid = 14r
remaining principle = 1400 - (800 - 14r) = 600 + 14r
Interest paid in second installment = (600 +14r) ) * r * 1/100
= 6r + 0.14r²
total interset paid in 2 months = Rs 200
14r + 6r + 0.14r² = 200
0.14r² + 20r - 200 = 0
7r² + 1000r - 10000 = 0
r = (- 1000 + √(1000000 + 280000) )/14
r = 9.38 % per month
r = 112.6 % per annum