The cost of a journey is given by the linear function C(d) = 100 + 60 d, where C indicates total cost Class 9

The cost of a journey is given by the linear function C(d) = 100 + 60 d, where C indicates total cost Class 9

Question 1.

The cost of a journey is given by the linear function C(d) = 100 + 60 d, where C indicates total cost in rupees and d the distance travelled in km. Class 9

What is the cost for travelling 15 km? For how many kilometres will the cost of the journey be ₹ 700?

Answer:

Substituting d = 15 in C(d) = 100 + 60d, we get

C(15) = 100 + (60 × 15) = 100 + 900 = 1000

∴ The cost for travelling 15 km is ₹ 1000.

ii. Cost of the journey C (d) = 700.

∴ 100 + 60d = 700

∴ 60d = 700 - 100 = 600

∴ d = $\frac{600}{60}$ = 10

∴ The cost of the journey will be ₹700 for a travel of 10 km.

Question 2.

The height of water in a cylindrical tank is 3 m at the start of summer. The height h m at the end of t months is given by the linear function h(t) = 3 - 0.51. Class 9

What will be the height of the water at the end of 5 months?

Answer:

Substituting t = 5 in h(t) = 3 - 0.5t, we get h(5) = 3 - (0.5 × 5) = 3 - 2.5 = 0.5

∴ The height of the water at the end of 5 months will be 0.5 m.