Question

You have the cards numbered 1-10 in front of you.Each time you select a card,it is returned.What is the probability of selecting a 3 and then an even number

Answer 1

Answer:

$Both \: the \: moon \: and \: earth \: are \: in \: \\ the \: shape \: of \: spheres. \\ Surface\: area \: of \: a \: sphere \: of \: radius \: 'r'$

Let d1 be the diameter of the moon and d2 and be the diameter of the earth.Let r1 be the radius of the moon and r2 be the radius of the earth.

$given \: d1 = \frac{1}{4}d2 \\ = > 2r1 = \frac{1}{4} ×2r2 \\ =>r1 = \frac{1}{4}×r2 \\ Now, \: ratio \: of \: \: their \: surface \: areas \: is: \\ = s1: s2 \\ = r {1}^{2}: r {2}^{2} \\ = {1}^{2 } : {4}^{2 } \\ =1:16$

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