When 14.6 × 103 k j of nutritional energy is consumed , 1 lb of fat is stored by the body.
It means amount of nutritional energy is directly proportional to amount of fat stored.
Now amount of fat required = 3 lb
A.T.Q
Amount of fat stored= K × Amount of nutritional energy taken

⇒

⇒

⇒
= 4511.4 kj
For 3 lb of fat 4511.4 k j of excess nutritional energy should be consumed.
It is not given that how many k j a bag contain, So we can't calculate the number of bags.