CBSE Notes, Lectures

CBSE - Mathematics - Surface Areas and Volumes

Surface Areas and Volumes

NCERT Exercise Exercise 13.4

The diameter of the moon is approximately one fourth of the diameter of the earth. Find the ratio of their surface areas

Let the diameter of earth be r and that of the moon will be r/4
Radius of the earth = r/2
Radius of the moon = r/8
Ratio of their surface area = 4π(r/8)2/4π(r/2)2
                                                    = (1/64)/(1/4)
                                          = 4/64 = 1/16
Thus, the ratio of their surface areas is 1:16

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