Question:
A telecom company charges ₹ 600 for a certain recharge scheme. This prepaid balance is reduced by ₹ 15 each day after the recharge.
(A) Write an equation that models the remaining balance b(x) after using the scheme for x days. Explain why it represents linear decay.
(B) After how many days will the balance run out?
(C) Make a table of values for x varying from 1 to 10 days and show how the balance b(x), reduces with time. [Page No. 26]
Answer:
Verified
(A) Balance equation: b(x) = 600 - 15x. It is linear decay since balance decreases by a constant ₹ 15 daily.
(B) Balance runs out when b(x) = 0
⇒ 600 - 15x = 0
⇒ x = 40 days.
(C) Table of values:
| x (days) | b(x) (₹) |
|---|---|
| 1 | 585 |
| 2 | 570 |
| 3 | 555 |
| 4 | 540 |
| 5 | 525 |
| 6 | 510 |
| 7 | 495 |
| 8 | 480 |
| 9 | 465 |
| 10 | 450 |
The balance decreases steadily by ₹ 15 each day, clearly showing a uniform linear drop.
