Question

a sum of money amount to RS.9800 after 5years and rs. 12005 after 8years at the same rate of simple interest then find the rate of interest per annum​

Answer 1

Answer:

Step-by-step explanation:

Given :-

Sum of money = Rs. 9800

Time = 5 years

Solution :-

Simple Interest for 3 years = (Rs.12005 - Rs.9800)

Simple Interest for 3 years = Rs. 2205

Simple Interest for 5 years =  2205/ 3  ×  5  

Simple Interest for 5 years =  Rs.  3675

Principal = (Rs.9800 - Rs.3675)

Principal = Rs. 6125

R =  100  ×  SI /P × T

R =  100  ×  3675/ 6125  ×  5

R  =  12 %

Hence, the rate of interest per annum​ is 12%.

Answer 2

$\LARGE\underline{\underline{\sf \red{G}\blue{i}\green{v}\orange{e}\red{n}:}}$

• amount after 5 years = 9800
• amount after 8 years = 12005

$\LARGE\underline{\underline{\sf \red{T}\blue{o}\:\green{F}\orange{i}\pink{n}\red{d}:}}$ Rate = ???

$\LARGE\underline{\underline{\sf \red{S}\blue{o}\green{l}\orange{u}\pink{t}\purple{i}\orange{o}\red{n}:}}$

we know that , in simple interest , our interest is sams every year,

so, in 3 years from 5 to 8 his amount increase because of interest only ,

increase amount in 3 years = 12005 - 9800 = 2205

so,

increase amount every year = 2205 /3 = 735 rs.

every year he got an interest of 735 rs ,

so, in first 5yrs his total Simple interest will be = 735 × 5 = 3675 Rs..

Now we know that ,

Principal = Amount - simple interest

Principal = 9800 - 3675 = 6125 Rs...

so,

Now our Rate is = (SI of 1 year × 100)/Principal

Rate = (735×100)/6125 = 12%

So, our Required rate is 12% .....

(Hope it helps you)