Simple Interest
Math MCQs

Question :    Betty took a loan of $6500 at the rate of 10% simple interest per annum. If he paid an amount of $12350 to clear the loan, then find the time period of the loan.

Correct Answer  9

Solution & Explanation

Solution

Given,

Principal (P) = $6500

Rate of Simple Interest (R) = 10% per annum

Amount (A) = $12350

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 = $12350 – $6500 = $5850

Thus, Simple Interest = $5850

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 × 5850}/_{6500 × 10}

= ⁵⁸⁵⁰⁰⁰/₆₅₀₀₀

= 9 years (using formula)

Thus, Time (T) = 9 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) = $6500

Rate of Simple Interest (R) = 10% per annum

Simple Interest = $5850 (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 = 10% of Principal

= 10% of $6500

= ¹⁰/₁₀₀ × 6500

= ^{10 × 6500}/₁₀₀

= ⁶⁵⁰⁰⁰/₁₀₀ = 650

Thus, simple Interest for 1 year = $650

Now,

∵ If the simple Interest is $650, then the time = 1 year

∴ If the simple Interest is $1, then the time = ¹/₆₅₀ years

∴ If the simple Interest is $5850, then the time = ¹/₆₅₀ × 5850 years

= ^{1 × 5850}/₆₅₀ years

= ⁵⁸⁵⁰/₆₅₀ = 9 years

Thus, time (T) = 9 years Answer

Similar Questions

(1) Calculate the amount due if Thomas borrowed a sum of $3800 at 2% simple interest for 3 years.

(2) What amount does John have to pay after 5 years if he takes a loan of $3200 at 6% simple interest?

(3) What amount will be due after 2 years if Mark borrowed a sum of $3700 at a 9% simple interest?

(4) Daniel had to pay $4346 in order to furnish the loan taken 3 years before. If the rate of simple interest was 2% then find the sum borrowed.

(5) Calculate the amount due if Jessica borrowed a sum of $3750 at 9% simple interest for 4 years.

(6) What amount does Charles have to pay after 6 years if he takes a loan of $3900 at 9% simple interest?

(7) What amount does Jessica have to pay after 5 years if he takes a loan of $3750 at 4% simple interest?

(8) Calculate the amount due if Barbara borrowed a sum of $3550 at 8% simple interest for 3 years.

(9) Calculate the amount due if Robert borrowed a sum of $3100 at 9% simple interest for 3 years.

(10) If Sarah paid $4158 to settle his loan which he had taken 4 years before at a simple interest of 2%, then find the loan taken.