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9th Class Mathematics Surface Areas and Volumes Question Bank Surface Area and Volume

  • question_answer
    10 cylindrical pillars of a building have to be painted. The radius of each pillar is 35 cm and the height is 2 m. what is the cost of painting at the rate of Rs 5 per sq m?

    A)  Rs 200                         

    B)  Rs 220         

    C)  Rs 280            

    D)  Rs 500

    Correct Answer: B

    Solution :

    (b): Given, r=35 cm, h= 2m \[\therefore \]Surface area of cylinder \[10(2\pi rh)\] \[=10\left( 2\times \frac{22}{7}\times 0.35\times 2 \right)=44\]m   \[\therefore \]Total cost of painting \[=44\times 5=Rs220\]  


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