A petrol tank is in the form of a frustum of a cone of height 20 m with diameters of its lower and upper ends as 20 m and 50 m respectively. Find the cost of petrol which can fill the tank completely at the rate of Rs. 70 per litre. Also find the surface area of the tank.
Answers
Answer:
Step-by-step explanation:
Height of cone = 20m
Diameter of lower end = 20m , r = 10m
Diameter of upper end = 50= 25m
Cost per litre = 70rs
Volume of lower cone = 1/3pi*r^2h
1/3*22/7*10*10*20=44000/21m^3
Volume of cube with upper cone = 1/3pi*r^2h
= 1/3*22/7*25*25*20
=275000/21m^3
Add both the volumes , you will get volume of complete cube
44000/21+275000/21 = 319000/21
Cost for filling petrol = 319000/21*70
= rs 7443333.33
Answer:
Total cost = Rs 14,28,700
Surface area of frustum = 2750 m² .
Step-by-step explanation:
Given :
Upper diameter = 50 m
= > Radius ( R ) = 25 m
Lower diameter = 20 m
= > Radius ( r ) = 10 m
Height ( h ) = 20 m
Now we know :
Volume of frustum of a cone = π h / 3 ( R² + r² + R r )
Putting value here :
= > π × 20 / 3 ( 25² + 10² + 250 ) m³
= > 6500 π m³
Now convert it into litres.
= > 6500 π × 10³ L
Now :
For 1 L = Rs 70
Total cost = Rs 6500 π × 10³ × 70
Total cost = Rs 6500 × 22 / 7 × 10³ × 70
Total cost = Rs 14,28,700
Now :
We know :
Surface area of frustum = π l × ( R + r )
l² = R² + r²
l = 25 m
Surface area of frustum = 22 /7 × 25 ( 25 + 10 ) m²
Surface area of frustum = 2750 m² .
Hence we get answer.