Simple Interest
MCQs Math


Question:     In how much time a principal of $3100 will amount to $3472 at a simple interest of 3% per annum?


Correct Answer  4

Solution And Explanation

Solution

Given,

Principal (P) = $3100

Rate of Simple Interest (R) = 3% per annum

Amount (A) = $3472

Thus, time (T) = ?

Method (1) Using Formula

Calculation of Simple Interest, when Principal and Amount are given

Formual to Calculate Simple Interest when Principal and Amount are given

We know that, Amount (A) = Principal (P) + Simple Interest (SI)

⇒ Simple Interest (SI) = Amount – Principal

⇒ SI = $3472 – $3100 = $372

Thus, Simple Interest = $372

Calculation of the Time using forumula when Amount, Simple Interest and Principal are known

Formula to find the Time (T)

Time (T) = 100 × Simple Interest/Principal × Rate of Interest

⇒ T = 100 × SI/P × R

Thus, Time (T) = 100 × 372/3100 × 3

= 37200/9300

= 4 years (using formula)

Thus, Time (T) = 4 years (from time taken before calculation)Answer

Calculation of the Time using Unitary Method when Amount, Simple Interest and Principal are known

Here, we have

Principal (P) = $3100

Rate of Simple Interest (R) = 3% per annum

Simple Interest = $372 (As calculated above by subtracting Principal from the Amount given)

We know that, interest is calculated on the basis of the Principal.

This means Simple Interest for 1 year = Rate of simple interest × Principal

Thus, Simple Interest for 1 year = 3% of Principal

= 3% of $3100

= 3/100 × 3100

= 3 × 3100/100

= 9300/100 = 93

Thus, simple Interest for 1 year = $93

Now,

∵ If the simple Interest is $93, then the time = 1 year

∴ If the simple Interest is $1, then the time = 1/93 years

∴ If the simple Interest is $372, then the time = 1/93 × 372 years

= 1 × 372/93 years

= 372/93 = 4 years

Thus, time (T) = 4 years Answer


Similar Questions

(1) Find the amount to be paid if Jennifer borrowed a sum of $5250 at 6% simple interest for 8 years.

(2) Find the amount to be paid if Joseph borrowed a sum of $5700 at 3% simple interest for 8 years.

(3) Thomas took a loan of $5600 at the rate of 9% simple interest per annum. If he paid an amount of $9128 to clear the loan, then find the time period of the loan.

(4) Find the amount to be paid if Susan borrowed a sum of $5650 at 8% simple interest for 7 years.

(5) David took a loan of $4800 at the rate of 6% simple interest per annum. If he paid an amount of $7392 to clear the loan, then find the time period of the loan.

(6) William took a loan of $5000 at the rate of 6% simple interest per annum. If he paid an amount of $6800 to clear the loan, then find the time period of the loan.

(7) Calculate the amount due if Susan borrowed a sum of $3650 at 4% simple interest for 3 years.

(8) If Paul paid $5264 to settle his loan which he had taken 4 years before at a simple interest of 3%, then find the loan taken.

(9) Calculate the amount due after 9 years if Richard borrowed a sum of $5600 at a rate of 10% simple interest.

(10) Find the amount to be paid if John borrowed a sum of $5200 at 7% simple interest for 7 years.


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