Question

Q.Difference between SI and CI is 35 in 2nd year but 77 in 3rd year at certain rate on principal . find principal and rate of interest​

Answer 1

Answer:

Let “P” be the principal, “R” the rate for three years compounded annually. Then,

Interest for 1st year = I

Interest for 2nd year = I + I’ (Where I2 is the interest on I1)

Interest for 3rd year = I + I’ + I’ + I”

Here simple interest for three years = 3I

Difference between CI and SI = 3I’ + I”

Now coming to the question-

Difference of CI and SI for 2nd year = 35

Difference of CI and SI for 3rd year = 77 = I + 35 + 35 + 7

Hence rate = 7/35 = 1/5 or 20%

Now, 1/5 = 35

or, 1 = 175, This is SI for one year

2.5 year = 2.5 * 175

= 437.5

Step-by-step explanation:

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