Answer:
Weight of a pile of sand = 90 Kg 
 
Ratio of weight of sand in three bags = 
2 : 3 : 7 
 
Let the weights be 2x kg, 3x kg and 7x kg respectively 
 
A.T.Q. 
 
=> 2x + 3x + 7x = 90 
 
=> 12x = 90 
 
=> x = 90/12 
 
=> x = 7.5 Kg 
 
 
___________________________ 
 
Weight of sand in small bag = 
 
=> 2 × 7.5 
 
=> 15 Kg ANS 
 
 
Weight of sand in medium bag = 
 
=> 3 × 7.5 
 
=> 22.5 Kg ANS 
 
 
Weight of sand in large bag = 
 
=> 7 × 7.5 
 
=> 52.5 Kg ANS