8th Class Mathematics Sample Paper Mathematics Sample Paper - 6

  • question_answer
    A road roller takes 750 complete revolutions to move once over to level a road. Find the area of road if the diameter of a road roller is 84 cm and length is 1 m.

    Answer:

    Diameter of road roller = 84 cm
    r = \[\frac{84}{2}=42\]cm
    = 0.42 m
    Length of road roller = 1 m                                                                            
    The shape of road roller is cylindrical, then
    1 revolution to move once over level the road
    = 1 surface area of road roller
    \[=\text{ }2\pi rh\]
                \[=2\times \frac{22}{7}\times 0.42\times 1\]
    \[=\text{ }2.64\text{ }{{m}^{2}}\]
    The area of 750 revolutions to level the road by a road roller
    \[=750\times 2.64\]
    \[=\text{ }1980\text{ }{{m}^{2}}\]


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