Simple Interest
Math MCQs

Question :    In how much time a principal of $3050 will amount to $3324.5 at a simple interest of 3% per annum?

Correct Answer  3

Solution & Explanation

Solution

Given,

Principal (P) = $3050

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

Amount (A) = $3324.5

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 = $3324.5 – $3050 = $274.5

Thus, Simple Interest = $274.5

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 × 274.5}/_{3050 × 3}

= ²⁷⁴⁵⁰/₉₁₅₀

= 3 years (using formula)

Thus, Time (T) = 3 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) = $3050

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

Simple Interest = $274.5 (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 $3050

= ³/₁₀₀ × 3050

= ^{3 × 3050}/₁₀₀

= ⁹¹⁵⁰/₁₀₀ = 91.5

Thus, simple Interest for 1 year = $91.5

Now,

∵ If the simple Interest is $91.5, then the time = 1 year

∴ If the simple Interest is $1, then the time = ¹/_91.5 years

∴ If the simple Interest is $274.5, then the time = ¹/_91.5 × 274.5 years

= ^{1 × 274.5}/_91.5 years

= ^274.5/_91.5 = 3 years

Thus, time (T) = 3 years Answer

Similar Questions

(1) Calculate the amount due if Christopher borrowed a sum of $4000 at 4% simple interest for 3 years.

(2) How much loan did Barbara borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $6937.5 to clear it?

(3) Calculate the amount due if Thomas borrowed a sum of $3800 at 7% simple interest for 4 years.

(4) Find the amount to be paid if David borrowed a sum of $5400 at 8% simple interest for 7 years.

(5) Calculate the amount due if Linda borrowed a sum of $3350 at 8% simple interest for 3 years.

(6) How much loan did Sarah borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $6435 to clear it?

(7) Calculate the amount due after 10 years if Elizabeth borrowed a sum of $5450 at a rate of 2% simple interest.

(8) Calculate the amount due if Sarah borrowed a sum of $3850 at 7% simple interest for 4 years.

(9) What amount will be due after 2 years if Donald borrowed a sum of $3750 at a 6% simple interest?

(10) Calculate the amount due if Thomas borrowed a sum of $3800 at 8% simple interest for 4 years.