The difference between C.I & S.I. on rs 14,000 for 2 years is rs 35 at the same rate of interest
per annum what is the rate of interest?
Answers
Solution!!
The concept of simple interest and compound interest has to be used here. The principal, time and the difference between the compound interest and simple interest is given in the question. We are asked to find the rate of interest.
We will first find the simple interest and then we will find the compound interest.
Principal = Rs 14000
Time = 2 years
Rate of interest = x
Simple interest = (P × R × T)/100
Here,
P → Principal
R → Rate of interest
T → Time
= (14000 × x × 2)/100
= 140 × x × 2
= 280x
Simple interest = 280x
Now, let's find the compound interest.
Principal (P) = Rs 14000
Rate of interest (R) = x
Time (n) = 2 years
Amount = P(1 + (R/100))ⁿ
Amount = 14000(1 + (x/100))²
Amount = 14000((100 + x)/100)²
Amount = 14000 × (100 + x)/100 × (100 + x)/100
Amount = 1.4 × (100 + x) × (100 + x)
Amount = 1.4 × (100 + x)²
Amount = 1.4 × (10000 + x² + 200x)
Amount = 14000 + 1.4x² + 280x
Amount = 1.4x² + 280x + 14000
Compound interest (CI) = Amount - Principal
CI = (1.4x² + 280x + 14000) - 14000
CI = 1.4x² + 280x
We know that the difference between the compound interest (CI) and simple interest (SI) is Rs 35. So,
CI - SI = 35
(1.4x² + 280x) - 280x = 35
1.4x² = 35
x² = 35 ÷ 1.4
x² = 25
x = √25
x = 5
Hence, the rate of interest is 5% per annum.
Rate of interest (R) = 5%
Solution!!
The concept of simple interest and compound interest has to be used here. The principal, time and the difference between the compound interest and simple interest is given in the question. We are asked to find the rate of interest.
We will first find the simple interest and then we will find the compound interest.
Principal = Rs 14000
Time = 2 years
Rate of interest = x
Simple interest = (P × R × T)/100
Here,
P → Principal
R → Rate of interest
T → Time
= (14000 × x × 2)/100
= 140 × x × 2
= 280x
Simple interest = 280x
Now, let's find the compound interest.
Principal (P) = Rs 14000
Rate of interest (R) = x
Time (n) = 2 years
Amount = P(1 + (R/100))ⁿ
Amount = 14000(1 + (x/100))²
Amount = 14000((100 + x)/100)²
Amount = 14000 × (100 + x)/100 × (100 + x)/100
Amount = 1.4 × (100 + x) × (100 + x)
Amount = 1.4 × (100 + x)²
Amount = 1.4 × (10000 + x² + 200x)
Amount = 14000 + 1.4x² + 280x
Amount = 1.4x² + 280x + 14000
Compound interest (CI) = Amount - Principal
CI = (1.4x² + 280x + 14000) - 14000
CI = 1.4x² + 280x
We know that the difference between the compound interest (CI) and simple interest (SI) is Rs 35. So,
CI - SI = 35
(1.4x² + 280x) - 280x = 35
1.4x² = 35
x² = 35 ÷ 1.4
x² = 25
x = √25
x = 5
Hence, the rate of interest is 5% per annum.
Rate of interest (R) = 5%