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Word Problem 2

Problem 2: On an investment interest at rate of 4% for 8 months term is Rs 129 less than the interest on the same amount at rate of 5% for 15 months. What is the value of investment (principal amount) ?



Solution:

simple arithmetic questions and answers

In the First Case;

R1=4,  T1 = 8/12

I1= \frac{P1\times R1\times T1}{100}

I1= \frac{y\times 4\times \frac{8}{12}}{100}

I1= \frac{8y}{300}

In the 2nd Case;

R2 =5,  T2= 15/12

I2= \frac{P2\times R2\times T2}{100}

I2= \frac{y\times 5\times \frac{15}{12}}{100}

I2= \frac{75y}{1200}

According to condition of question;

I2-I1=129

\Rightarrow \frac{75y}{1200} -\frac{8y}{300}= 129

\Rightarrow \frac{75y-32y}{1200} = 129

\Rightarrow \frac{43y}{1200} = 129

\Rightarrow y =\frac{129\times 1200}{43}

\Rightarrow y =3600

So, the principal amount was Rs 3600