## RD Sharma Class 8 Solutions Chapter 14 Compound Interest Ex 14.4

These Solutions are part of RD Sharma Class 8 Solutions. Here we have given RD Sharma Class 8 Solutions Chapter 14 Compound Interest Ex 14.4

**Other Exercises**

**Question 1.****The present population of a town is 28,000. If it increases at the rate of 5% per annum, what will be its population after 2 years ?****Solution:**

Present population = 28000

Rate of increase (R) = 5% p.a.

Period (n) = 2 years

Population after 2 years

**Question 2.****The population of a city is 125000. If the annual birth rate and death rate are 5.5% and 3.5% respectively, calculate the population of city after 3 years.****Solution:**

Present population = 125000

Rate of birth = 5.5%

and rate of death = 3.5%

Increase = 5.5 – 3.5 = 2% p.a.

Period = 3 years.

Population after 3 years

**Question 3.****The present population of a town is 25000. It grows at 4%, 5% and 8% during first year, second year and third year respectively. Find its population after 3 years.****Solution:**

Present population = 25000

Increase in first year = 4%

in second year= 5% and

in third year = 8%

Population after 3 years =

**Question 4.****Three years ago, the population of a town was 50000. If the annual increase during three successive years be at the rate of 4%, 5% and 3% respectively, find the present population.****Solution:**

Three years ago,

Population of a town = 50000

Annual increase in population in first year = 4%

in second year = 5%

and in third year = 3%

Present population

**Question 5.****There is a continuous growth in population of a village at the rate of 5% per annum. If its present population is 9261, what it was 3 years ago ?****Solution:**

Let 3 years ago, population = P

Present population = 9261

Rate of increase (R) = 5% p.a.

Period (n) = 3 years.

**Question 6.****In a factory, the production of scooters rose to 46305 from 40000 in 3 years. Find the annual rate of growth of the production of scooters.****Solution:**

Production of scooters 3 years ago (P) = 40000

Present production (A) = 46305

Period (n) = 3 years

**Question 7.****The annual rate of growth in population of a certain city is 8%. If its present population is 196830, what it was 3 years ago ?****Solution:**

Let 3 years ago, the population of a city = P

Rate of growth (R) = 8% p.a.

Present population = 196830

Period (n) = 3 years

**Question 8.****The population of a town increases at the rate of 50 per thousand. Its population after 2 years will be 22050. Find its present population.****Solution:**

Population after 2 years = 22050

Rate of increase = 50 per thousand

Period (n) = 2 years

Let present population = P, then

**Question 9.****The count of bacteria in a culture grows by 10% in the first hour, decreases by 8% in the second hour and again increases by 12% in the third hour. If the count of bacteria in the sample is 13125000, what will be the count of bacteria after 3 hours ?****Solution:**

Present count of bacteria = 13125000

In first hour increase = 10%

decrease in second hour = 8%

increase in third hour = 12%

Count of bacteria after 3 hours

**Question 10.****The population of a certain city was 72000 on the last day of the year 1998. During next year it increased by 7% but due to an epidemic it decreased by 10% in the following year. What was its population at the end of the year 2000 ?****Solution:**

On the last day of 1998,

Population of a town = 72000

In the first year, increase = 7%

In the second year, decrease = 10%

Population in the last day of 2000

**Question 11.****6400 workers were employed to construct a river bridge in four years. At the end of the first year, 25% workers were retrenched. At the end of the second year, 25% of those working at that time were retrenched. However, to complete the project in time, the number of workers was increased by 25% at the end of the third year. How many workers were working during the fourth year ?****Solution:**

Number of workers at the beginning = 6400

Period = 4 years.

At the end of 1st year, workers retrenched = 25%

At the end of second year, workers retrenched = 25%

At the end of third year, workers increased = 25%

Total number of workers during the 4 years

**Question 12.****Aman started a factory with an initial investment of Rs 1,00,000. In the first year, he incurred a loss of 5%. However, during the second year, he earned a profit of 10% which in the third year rose to 12%. Calculate his net profit for the entire period of three years.****Solution:**

Initial investment = Rs 100000

Loss in the first year = 5%

Profit in the second year = 10%

Profit in the third year = 12%

Investment at the end of 3 years

**Question 13.****The population of a town increases at the rate of 40 per thousand annually. If the present population be 175760, what was the population three years ago ?****Solution:**

Present population (A) = 175760

Increase rate = 40 per 1000

Period = 3 years

Let 3 years ago,

population was = P

**Question 14.****The production of a mixi company in 1996 was 8000 mixies. Due to increase in demand it increases its production by 15% in the next two years and after two years its demand decreases by 5%. What will be its production after 3 years ?****Solution:**

Production of Mixi in 1996 = 8000

Increase in next 2 years = 15%

Decrease in the third year = 5%

Production after 3 years

**Question 15.****The population of a city increases each year by 4% of what it had been at the beginning of each year. If the population in 1999 had been 6760000, find the population of the city in (i) 2001 (ii) 1997.****Solution:**

Population of a city in 1999 = 6760000

Increase = 4%

(i) Population in 2001 is after 2 years

**Question 16.****Jitendra set up a factory by investing Rs 25,00,000. During the first two successive years his profits were 5% and f 10% respectively. If each year the profit was on previous year’s capital, compute his total profit.****Solution:**

Investment in the beginning = Rs 25,00,000

Profit during the first 2 years = 5% and 10% respectively

Investment after 2 years will be

= Rs 28,87,500

Amount of profit = Rs 28,87,500 – Rs 25,00,000 = Rs 3,87,500

Hope given RD Sharma Class 8 Solutions Chapter 14 Compound Interest Ex 14.4 are helpful to complete your math homework.

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