In what time will the interest on 3600 at the rate of 10% be equal to the interest on 1800 at the rate of 12.5% in 4 years?

Calculating Interest and Excel Functions:

The simplest type of interest is called, appropriately, “simple interest.” If you were to loan a friend $1000 to start a business and you both agreed that in one year, the friend would repay you $1060, you would earn $60 interest on that investment.

You would earn $60 simple interest. Simple interest is calculated as a percentage of the initial amount borrowed and does not include any additional earnings.

The percentage of the original loan amount that is paid as simple interest is called the interest rate. In our example, the interest rate on a $1000 loan that requires a $60 interest payment in one year is:

\(\frac{60}{1000}=0.06 \:\text{or}\:6\%\)

The simple interest rate on this loan would be 6%.

• Interest Rate = The amount earned on an investment or charged on a loan (% of the principal)
• Principal = The original amount of money borrowed for a loan or placed into an investment

Video Source (06:53 mins) | Transcript

The following video shows another example of simple interest and explains how this works with a little more detail.

Video Source (03:44 mins) | Transcript

There are two perspectives on interest. Someone is the lender, and someone is the borrower. From the viewpoint of the lender, interest is great. It allows them to make money on their investment. From the perspective of the borrower, interest can be a big problem. In addition to paying back the original amount of the loan, the borrower must also pay the interest.

The higher the interest rate, the greater the interest payment will be.

Interest Equation: I = Prt

• I = Interest
• P = Principle
• r = Rate (using the decimal form of the %)
• t = Time

Amount Owed = P + I

Additional Resources

• Khan Academy: Intro to Simple Interest (02:45 mins, Transcript)
• Khan Academy: Finding Simple Interest for One Year (05:22 mins, Transcript)
• Khan Academy: Finding Simple Interest for Many Years (08:03 mins, Transcript)

Practice Problems

1. What is the definition for each of the variables in the simple interest formula (I=Prt)?


2. How much interest will you earn if you invest $500 for three years at a simple interest rate of 4% annually?


3. How much interest will you earn if you invest $1000 for seven years at a simple interest rate of 8% annually?


4. What is the total amount of money that you will have at the end of the four years if you invest $2000 for four years at a simple interest rate of 8% annually?


5. What is the total amount of money that you will have at the end of the six years if you invest $900 for six years at a simple interest rate of 7% annually?

• Textbook Solutions
• Class 7
• Math
• banks and simple interest

Mathematics_(solutions) Solutions for Class 7 Math Chapter 11 Banks And Simple Interest are provided here with simple step-by-step explanations. These solutions for Banks And Simple Interest are extremely popular among Class 7 students for Math Banks And Simple Interest Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Mathematics_(solutions) Book of Class 7 Math Chapter 11 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Mathematics_(solutions) Solutions. All Mathematics_(solutions) Solutions for class Class 7 Math are prepared by experts and are 100% accurate.

Page No 73:

Question 1:

If Rihanna deposits 1500 rupees in the school fund at 9 p.c.p.a for 2 years, what is the total amount she will get?

Answer:

Given:
Principal (P) = 1500 rupees,
Rate of interest (R) = 9%
Time (T) = 2 years
Total interest (I) = P×R×T100
=1500×9×2100
= 270 rupees
Now, total amount = P + I
= 1500 + 270
= 1770 rupees
 Hence, Rihanna will get the total amount of 1770 rupees.

Page No 73:

Question 2:

Jethalal took a housing loan of 2,50,000 rupees from a bank at 10 p.c.p.a. for 5 years. What is the yearly interest he must pay and the total amount he returns to the bank?

Answer:

Given:
Principal (P) = 250000 rupees,
Rate of interest (R) = 10%
Time (T) = 5 years
Total interest (I) = P×R×T100
=250000×10×5100
= 125000 rupees
Now, total amount = P + I
= 2500000 + 125000
= 375000 rupees
 Hence, Jethalal will have to pay 125000 rupees as an interest and 375000 as the the total amount to the bank.

Page No 73:

Question 3:

Shri kant deposited 85,000 rupees for 212 years at 7 p.c.p.a. in a savings bank account. What is the total interest he received at the end of the period?

Answer:

Given:
Principal (P) = 85000 rupees,
Rate of interest (R) = 7%
Time (T) = 212 years
= 52 years
Total interest (I) = P×R×T100
=85000×7×52×100
= 14875 rupees
 Hence, Shrikant will receive 14875 rupees as an interest from the bank.

Page No 73:

Question 4:

At a certain rate of interest, the interest after 4 years on 5000 rupees principal is 1200 rupees. What would be the interest on 15000 rupees at the same rate of interest for the same period?

Answer:

Given:
Principal (P) = 5000 rupees,
Time (T) = 4 years
Total interest (I) = 1200
 Rate of interest (R) = I×100P×T
=1200 ×1005000×4
= 6%
Now, Total interest (I) on 15000 rupees = P×R×T100
=15000×6×4100
= 3600 rupees
 Hence, the rate of interest for the same period is 3600 rupees.

Page No 73:

Question 5:

If Pankaj deposits 1,50,000 rupees in a bank at 10 p.c.p.a. for two years, what is the total amount he will get from the bank ?

Answer:

Given:
Principal (P) = 150000 rupees,
Rate of interest (R) = 10%
Time (T) = 2 years
Total interest (I) = P×R×T100
=150000×10×2100
= 30000 rupees
Now, total amount = P + I
= 150000 + 30000
= 180000 rupees
 Hence, Pankaj will get the total amount of 180000 rupees from the bank.

Page No 74:

Question 1:

If the interest on 1700 rupees is 340 rupees for 2 years the rate of interest must be ......... .
 (i) 12 %
(ii) 15 %
(iii) 4 %
(iv) 10 %

Answer:

Given:
Principal (P) = 1700 rupees,
Total interest (I) = 340 rupees
Time (T) = 2 years

Rate of interest (R) =  I×100P×T
=340×1001700×2
= 10%
 Hence, the correct option is (iv).

Page No 74:

Question 2:

If the interest on 3000 rupees is 600 rupees at a certain rate for a certain number of years, what would the interest be on 1500 rupees under the same conditions ?
(i) 300 rupees
(ii) 1000 rupees
(iii) 700 rupees
(iv) 500 rupees

Answer:

The interest on 3000 rupees is 600 rupees
The interest on 1 rupee is 6003000rupees
The interest on 1500 rupee is 6003000 ×1500=300 rupees
 Hence, the correct option is (i).

Page No 74:

Question 3:

Javed deposited 12000 rupees at 9 p.c.p.a. in a bank for some years, and withdrew his interest every year. At the end of the period, he had received altogether 17,400 rupees. For how many years had he deposited his money ?

Answer:

Given:
Principal (P) = 12000 rupees,
Rate of interest (R) = 9%
Total Amount = 17400 rupees
Total interest (I) = 17400 − 12000
= 5400 rupees
Time (T) = I×100P×R
=5400×10012000×9
= 5 years
Hence, Javed  had deposited the money for 5 years.

Page No 74:

Question 4:

Lataben borrowed some money from a bank at a rate of 10 p.c.p.a. interest for 212 years to start a cottage industry. If she paid 10250 rupees as total interest, how much money had she borrowed ?

Answer:

Given:
Total interest (I) = 10250 rupees
Rate of interest (R) = 10%
Time (T) = 212
= 52 years
Principal (P) = I×100R×T
=10250×100×210×5
= 41000 rupees
Hence, Lataben  had deposited 41000 rupees in a bank.

Page No 74:

Question 5:

Fill in the blanks in the table.

Answer:

(i)
Given:
Principal (P) = 4200 rupees,
Rate of interest (R) = 7%
Time (T) = 3 years
Total interest (I) = P×R×T100
= 4200×7×3100
= 882 rupees
Total Amount = P + I
= 4200 + 882
= 5082 rupees

(ii)

Given:
Total interest (I) = 1200 rupess
Rate of interest (R) = 6%
Time (T) = 4 years
Principal (P) = I×100R×T
= 1200×1006×4
= 5000 rupees
Total Amount = P + I
= 5000 + 1200
= 6200 rupees

(iii)
​
Given:
Principal (P) = 8000 rupees
Total interest (I) = 800 rupess
Rate of interest (R) = 5%
Time (T) = I×100P×R
= 800×1008000×5
= 2 years
Total Amount = P + I
= 8000 + 800
= 8800 rupees

(iv)
​
Given:
Principal (P) = 8000 rupees
Total interest (I) = 6000 rupess
Now, Principal (P) = Total Amount − I
= 18000 − 6000
= 12000 rupees​
Rate of interest (R) = 5%
Time (T) = I×100P×R
= 6000× 10012000×5
= 10 years

(v)

Given:
Total interest (I) = 2400 rupess
Rate of interest (R) = 212%
= 52%
Time (T) = 5 years
Principal (P) = I×100R×T
= 2400×100×25×5
= 19200 rupees
Total Amount = P + I
= 19200 + 2400
= 21600 rupees

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