# Thread: Calculating % of water and energy content

1. ## Calculating % of water and energy content

I'm not sure if the Math Help Forum is the right place to ask these questions but I'm desperate.

I have a lab due tomorrow and I have no idea how to answer these questions:

1. 2.0 oz of spaghetti (56 g) has 200 kcal and contains 7 g of protein. It has essentially no fat. Both carbohydrates and proteins provide about 4.0 kcal/g. Calculate the percentage of water in spaghetti.

2. Brown eggs sold by Trader Joe's each weigh 56 g and contain 5 g fat, 1 g of carbohydrates and 7 g protein. Calorie content of fats, carbs and proteins are respectively 9, 4, and 4 kcal/g. Calculate the energy content of a single brown egg.

3. A typical low fat 4.0 oz sample of hamburger meat provides 245 kcal and has 17 g fat. Calculate the percentage of water in this hamburger meat.

Thanks.

2. ## might me wrong, but...

sorry, but i can only TRY to help u.
if the spag.(56g) only contains carbohydrate, protein and water and ifcarbohydrate, protein are the only source of energy. Then the 7 g protein provides 28 kcal, but the 56g spag. gives 200kcal,
Thus the energy provided by carbo =(200-28)kcal=172kcal,but since carbo givs 4 kcal/g, carbo in the spag weighs 172/4 g= 43g
Thus carbo and protein 2gether weigh 43g +7 g = 50g, assuming the only other component is water, it must weigh 56g-50g=16g
thus % of H20 by mass=16/56 .100%=25%

PS plz check for calculation errors, also i am only attempting, i do not garantee a correct answer, the other questions can be solved in similiar manner