Multiple choice

The simple interest on a sum of money is 1 121 of the principal and the rate of interest per annum is equal to the time taken to earn that interest. What will be the rate of interest per annum?

  1. 10 11 %

  2. 9%

  3. 7.8%

  4. 10 9 %

  5. 6.8%
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The simple interest fraction is rt/100 = 1/121, and the rate equals the time, so r^2/100 = 1/121. Taking the positive root gives r = 10/11%, matching option A.

AI explanation

Let the principal be P, the rate be R, and the time be T. Given the simple interest is 1/121 of the principal and the rate equals the time, we use the formula P times R times T divided by 100 equals P divided by 121. Substituting T with R gives R squared divided by 100 equals 1 divided by 121, so R squared equals 100 divided by 121, meaning the rate of interest is 10/11 percent.

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