Question 3
The initial population of a village is 750. Every year, 50 people move from a nearby city to the village.
(i) Find the population of the village after 6 years.
(ii) Make a table of values for varying from 0 to 10 years and show how the population, , increases every year.
(iii) Find an expression that relates and , and explain why it represents linear growth.
The village population grows by a fixed number of people each year.
Step 1 — Calculate population after 6 years
We start with the initial population. People move in every year. We need to find the total increase. Then, we add it to the initial population.
Step 2 — Create the population table
Let's make a table. We will show population for each year. The population starts at 750. It increases by 50 each year.
| t (years) | P (population) | |---|---| | 0 | 750 | | 1 | 800 | | 2 | 850 | | 3 | 900 | | 4 | 950 | | 5 | 1000 | | 6 | 1050 | | 7 | 1100 | | 8 | 1150 | | 9 | 1200 | | 10 | 1250 |
Step 3 — Find the expression and explain linear growth
Let be the population. Let be the number of years. The initial population is 750. The population increases by 50 each year. So, after years, the increase is . We add this to the initial population.
This represents linear growth. The population increases by a constant amount. It increases by 50 people every year. This constant rate of change defines linear growth.
Answer
(i) The population of the village after 6 years is 1050. (ii) | t (years) | P (population) | |---|---| | 0 | 750 | | 1 | 800 | | 2 | 850 | | 3 | 900 | | 4 | 950 | | 5 | 1000 | | 6 | 1050 | | 7 | 1100 | | 8 | 1150 | | 9 | 1200 | | 10 | 1250 | (iii) The expression relating and is . This represents linear growth because the population increases by a constant number (50 people) every year.
More questions in Exercise 2.4
Suppose a plant has height 1.75 feet and it grows by 0.5 feet each month.
(i) Find the height after 7 months.
(ii) Make a table of values for varying from 0 to 10 months and show how the height, , increases every month.
(iii) Find an expression that relates and , and explain why it represents linear growth.
A mobile phone is bought for ₹10,000. Its value decreases by ₹800 every year.
(i) Find the value of the phone after 3 years.
(ii) Make a table of values for varying from 0 to 8 years and show how the value of the phone, , depreciates with time.
(iii) Find an expression that relates and , and explain why it represents linear decay.
The initial population of a village is 750. Every year, 50 people move from a nearby city to the village.
(i) Find the population of the village after 6 years.
(ii) Make a table of values for varying from 0 to 10 years and show how the population, , increases every year.
(iii) Find an expression that relates and , and explain why it represents linear growth.
A telecom company charges ₹600 for a certain recharge scheme. This prepaid balance is reduced by ₹15 each day after the recharge.
(i) Write an equation that models the remaining balance after using the scheme for days. Explain why it represents linear decay.
(ii) After how many days will the balance run out?
(iii) Make a table of values for varying from 1 to 10 days and show how the balance reduces with time.