A sum of money becomes 8/5 of itself in 5 years at a certain rate of simple interest. Find the rate of interest???​

Answer : 12%

explanation :

Let the sum of money be P(which is the principal value) and rate of interest be R.

According to the question,

Amount (principal +simple interest) = 8P/5

Time (T) = 5 years

Simple interest (SI) = PRT/100

SI = 5PR/100

Amount = P +SI

8P/5 = P+(5PR/100)

8P/5 = P(100+5R)/100

160 = 100 +5R

5R =60

R = 12

Therefore, rate of interest = 12% p.a.

the answer to the question is a  

it has the same slope and the same y-intercept.

the direct variation says that:

then the equation is of the form is given by:

            where k is the constant variation.

from the given table:

consider any value of x and m(x)=y

x = 2 and m(x)=y = 3

substitute these value in [1]; we have;

divide both sides by 2 we get;

⇒

check:

put x = -1 and m(x) = -1.5

substitute in the equation:

-1.5 = -1.5                   true

therefore, the function m(x) represents a direct variation

graph of this function as shown below: