Simple Interest
Math MCQs

Question :    Robert took a loan of $4200 at the rate of 9% simple interest per annum. If he paid an amount of $6846 to clear the loan, then find the time period of the loan.

Correct Answer  7

Solution & Explanation

Solution

Given,

Principal (P) = $4200

Rate of Simple Interest (R) = 9% per annum

Amount (A) = $6846

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 = $6846 – $4200 = $2646

Thus, Simple Interest = $2646

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 × 2646}/_{4200 × 9}

= ²⁶⁴⁶⁰⁰/₃₇₈₀₀

= 7 years (using formula)

Thus, Time (T) = 7 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) = $4200

Rate of Simple Interest (R) = 9% per annum

Simple Interest = $2646 (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 = 9% of Principal

= 9% of $4200

= ⁹/₁₀₀ × 4200

= ^{9 × 4200}/₁₀₀

= ³⁷⁸⁰⁰/₁₀₀ = 378

Thus, simple Interest for 1 year = $378

Now,

∵ If the simple Interest is $378, then the time = 1 year

∴ If the simple Interest is $1, then the time = ¹/₃₇₈ years

∴ If the simple Interest is $2646, then the time = ¹/₃₇₈ × 2646 years

= ^{1 × 2646}/₃₇₈ years

= ²⁶⁴⁶/₃₇₈ = 7 years

Thus, time (T) = 7 years Answer

Similar Questions

(1) Calculate the amount due if Elizabeth borrowed a sum of $3450 at 6% simple interest for 3 years.

(2) What amount does Mary have to pay after 6 years if he takes a loan of $3050 at 5% simple interest?

(3) Anthony took a loan of $6600 at the rate of 9% simple interest per annum. If he paid an amount of $11946 to clear the loan, then find the time period of the loan.

(4) Calculate the amount due if Linda borrowed a sum of $3350 at 4% simple interest for 3 years.

(5) What amount does Thomas have to pay after 6 years if he takes a loan of $3800 at 7% simple interest?

(6) Find the amount to be paid if Richard borrowed a sum of $5600 at 5% simple interest for 8 years.

(7) Karen had to pay $4542.5 in order to furnish the loan taken 3 years before. If the rate of simple interest was 5% then find the sum borrowed.

(8) In how much time a principal of $3050 will amount to $3172 at a simple interest of 2% per annum?

(9) In how much time a principal of $3100 will amount to $3410 at a simple interest of 5% per annum?

(10) Calculate the amount due after 9 years if Sarah borrowed a sum of $5850 at a rate of 10% simple interest.