Q. 7

The base area of a right circular cone is 21m. and height is 14m. Let us calculate the expenditure to colour the curved surface at the rate of 1.50 per sq.m.

Answer :

Let, base radius of the cone = r m


According to problem,


πr2 = 21


r2 = 21 ×7/22


r = 2.58


radius of the base = 2.58 m


Height of the cone = 14 m


slant height of the cone,


= √(2.582 + 142)


= √(6.66 + 196)


= 14.24 cm


curved surface area of the cone,


= πrl


= 22/7 × 2.58 × 14.24


= 115.47 sq. m


Expenditure to colour the curved surface area,


= 115.47 × 1.50


= Rs. 173.2


Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Circular MotionCircular MotionCircular Motion46 mins
Reading the Right WayReading the Right WayReading the Right Way38 mins
Maxwell's Right Hand Thumb RuleMaxwell's Right Hand Thumb RuleMaxwell's Right Hand Thumb Rule43 mins
Can we be Right or Left Brain?Can we be Right or Left Brain?Can we be Right or Left Brain?41 mins
All About Maxwell's Right Hand Thumb RuleAll About Maxwell's Right Hand Thumb RuleAll About Maxwell's Right Hand Thumb Rule31 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
caricature
view all courses
RELATED QUESTIONS :

The quantity of iron sheet to make boya of right circular conical shape is m2. If the slant height of it is 5m, then let us write, by calculating, the volume of air in the boya and its height. Let us determine the expenditure to colour the whole surface of the boya at the rate of 2.80 per m2. [The width of the iron-sheet not to be considered while calculating.]

West Bengal Board - Mathematics