Question

solve 3 fast tell how we solve it both 3 and 4

Answer 1

3.surface area of a cube formulae 6a square they gave surface area =486 then 6a square =486
a square = 486/6
a square=81
a=root 81
a=9

Answer 2

here u have 2 choices hardwork or smart work
look at 3rd q
hardwork :multiply each option by 6 x square of that option and match the ans
smart work : divide 486 with 6 u get 81.. u know that 9 square is 81 ... this will help u

4. convert CM to meter
we know that, 100 CM =1 m
so 40 cm and 20 CM will be 0.4 and 0.2 meters respectively... get the volume
0.4 x 0.2 x9 = 0.08 x 9 =0.72
1 CM cube is 50 kg
then 0.72 CM cube will be 0.72 x 50 = 36 option c