Question

Petra invests $10 800. After 4 years she has earned $3240 in interest. At what amount rate of interest did she invest her money?

I need a detailed explanation please with every single detail, no matter how little it is. Thank you

Answer 1

Answer:

rate of interest = 7.5%

Step-by-step explanation:

principal = 10800

time = 4years

let, rate of interest = r%

formula, interest = prt/100

or, 3240 = 10800*4*r/100

or, r = 3240*100/10800*4

or, r = 7.5 %

Answer 2

Answer:

7.5%

Step-by-step explanation:

We have,

P = 10800

Time(T) = 4 years

SI = 3240.

Now,

∴ SI = PRT/100

=> 3240 = (10800 * R * 4)/10

=> 324000 = 10800 * 4R

=> 30 = 4R

=> R = 7.5%

Therefore, rate of interest = 7.5%

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