A sum invested at 5% simple interest p.a. grows to Rs.504 in 4yrs. The same amount at 10% simple interest p.a. in 21/2 yrs will grow to:a.Rs. 525b.Rs. 550c.Rs. 420d.Rs. 450

To solve this problem, we can use the formula for simple interest:

Simple Interest = (Principal * Rate * Time) / 100

Let's first calculate the principal amount using the given information. We know that the sum invested at 5% simple interest per annum grows to Rs. 504 in 4 years. Using the formula, we can write:

504 = (Principal * 5 * 4) / 100

Simplifying this equation, we get:

504 = (20 * Principal) / 100

Multiplying both sides by 100 and dividing by 20, we find:

Principal = (504 * 100) / 20 Principal = 2520 / 20 Principal = Rs. 126

Now, we need to find the amount that will grow to in 2.5 years at 10% simple interest per annum. Again, using the formula, we have:

Amount = Principal + Simple Interest Amount = Principal + (Principal * Rate * Time) / 100

Substituting the values, we get:

Amount = 126 + (126 * 10 * 2.5) / 100 Amount = 126 + (126 * 25) / 100 Amount = 126 + 3150 / 100 Amount = 126 + 31.5 Amount = Rs. 157.5

Therefore, the amount will grow to Rs. 157.5 in 2.5 years at 10% simple interest per annum. However, none of the given options match this amount.

To solve this problem, we can use the formula for simple interest:

Simple Interest = (Principal * Rate * Time) / 100

Let's first find the principal amount using the given information. We know that the sum invested at 5% simple interest per annum grows to Rs. 504 in 4 years. Using the formula, we can calculate the principal amount:

504 = (Principal * 5 * 4) / 100

Simplifying this equation, we get:

504 = (20 * Principal) / 100

Multiplying both sides by 100 and dividing by 20, we find:

Principal = (504 * 100) / 20 Principal = 2520 / 20 Principal = Rs. 126

Now, we need to find the amount that the same principal will grow to at 10% simple interest per annum in 2.5 years. Again, using the formula for simple interest, we can calculate the amount:

Amount = Principal + Simple Interest Amount = Principal + (Principal * Rate * Time) / 100

Substituting the values, we get:

Amount = 126 + (126 * 10 * 2.5) / 100 Amount = 126 + (126 * 25) / 100 Amount = 126 + 3150 / 100 Amount = 126 + 31.5 Amount = Rs. 157.5

Therefore, the same amount at 10% simple interest per annum in 2.5 years will grow to Rs. 157.5. However, none of the given options match this amount.