Question

The SI on a certain sum for 3.5 years at 7% p.a. is rs.225 more than the simple interest on the same sum for 4 years at 5% p.a. Find the sum.

Answer 1

$\huge\boxed{\texttt{\fcolorbox{red}{aqua}{Hey Mate!!!}}}$
$<b><i><font face=Copper black size=4 color=blue>$
Here is your answer
Let the principal is x

Now
For first case
Simple interest =
$= \frac{x \times 3.5 \times 7}{100} \\ = \frac{24.5x}{100}$
For second Case
Simple interest is
$= \frac{x \times 4 \times 5}{100} \\ \\ = \frac{x}{5}$
ATQ
$\frac{24.5x}{100} = \frac{x}{5} + 225 \\ \\ 500\times \frac{24.5x}{100} = \frac{x}{5} \times 500 + 225 \times 500 \\ 122.5x = 100x + 112500 \\ 122.5x - 100x = 112500 \\ 22.5x = 112500 \\ x = \frac{112500}{22.5} \\ x = 5000$
Therefore Principal is Rs 5000


$\large{\red{\boxed{\boxed{\boxed{\boxed{\boxed{\boxed{\boxed{\boxed{\boxed{\boxed{\underline{\underline{\underline{Hope\:it\:helps\: you}}}}}}}}}}}}}}}$

$\huge\boxed{\texttt{\fcolorbox{Red}{yellow}{Be brainly!!!}}}$

$<marquee>$
$\huge\bf{\red{\huge{\bf{@.....rajeev378}}}}$

Answer 2

Answer:

Let the sum or principal be x

Case 1

Given, p= x, T = 3 years, R = 12% p.a.

We know,      SI = P*R*T/100

putting value,  SI = X*12*3/100 = 9x/25

Case 2

Given, P= x, T = 3 years, r = 10.5% p.a.

We know,      SI = P*R*T/100

Putting values,  SI = X*2*10.5/100 = X*21/100 = 2x/100

Now, SI of case 1 is ₹ 375 more than SI of case 2

Or,     SI of case 1 - SI of case 2 = ₹375

9x/25-21x/100 = ₹375

36x - 21x /100 = ₹375

15x/100 = ₹375

x = ₹375 * 100 /15 = ₹2,500

Hence, the requried sum/principal is ₹ 2,500.