Simple Interest
Math MCQs

Question :    Jessica took a loan of $5500 at the rate of 8% simple interest per annum. If he paid an amount of $8580 to clear the loan, then find the time period of the loan.

Correct Answer  7

Solution & Explanation

Solution

Given,

Principal (P) = $5500

Rate of Simple Interest (R) = 8% per annum

Amount (A) = $8580

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 = $8580 – $5500 = $3080

Thus, Simple Interest = $3080

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 × 3080}/_{5500 × 8}

= ³⁰⁸⁰⁰⁰/₄₄₀₀₀

= 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) = $5500

Rate of Simple Interest (R) = 8% per annum

Simple Interest = $3080 (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 = 8% of Principal

= 8% of $5500

= ⁸/₁₀₀ × 5500

= ^{8 × 5500}/₁₀₀

= ⁴⁴⁰⁰⁰/₁₀₀ = 440

Thus, simple Interest for 1 year = $440

Now,

∵ If the simple Interest is $440, then the time = 1 year

∴ If the simple Interest is $1, then the time = ¹/₄₄₀ years

∴ If the simple Interest is $3080, then the time = ¹/₄₄₀ × 3080 years

= ^{1 × 3080}/₄₄₀ years

= ³⁰⁸⁰/₄₄₀ = 7 years

Thus, time (T) = 7 years Answer

Similar Questions

(1) Find the amount to be paid if Susan borrowed a sum of $5650 at 10% simple interest for 7 years.

(2) Find the amount to be paid if Mary borrowed a sum of $5050 at 6% simple interest for 7 years.

(3) Calculate the amount due after 10 years if Elizabeth borrowed a sum of $5450 at a rate of 3% simple interest.

(4) Find the amount to be paid if David borrowed a sum of $5400 at 4% simple interest for 7 years.

(5) Find the amount to be paid if Elizabeth borrowed a sum of $5450 at 2% simple interest for 8 years.

(6) What amount does Barbara have to pay after 5 years if he takes a loan of $3550 at 4% simple interest?

(7) In how much time a principal of $3150 will amount to $3937.5 at a simple interest of 5% per annum?

(8) In how much time a principal of $3100 will amount to $3348 at a simple interest of 4% per annum?

(9) What amount does Christopher have to pay after 6 years if he takes a loan of $4000 at 7% simple interest?

(10) Calculate the amount due after 10 years if William borrowed a sum of $5500 at a rate of 6% simple interest.