Firstly, we calculate the amount of stones in the adulterated rice
5 kg x 2,72/100 = 0,136 kgs of stones
then 5 Kgs of adulterated rice is made up of 4,864 kgs of pure rice and 0,136 Kgs of stones
Secondly,
We remove 0,136/2 = 0,068 Kgs of stones
then, we have 4,864 Kgs of pure rice and 0,068 Kgs of stones
Finally, the percentage of stones is calculated as follows
0,068 / ( 4,864 + 0,068) x 100 = 1,378 %