J.R. S. answered • 05/17/17
Tutor
5.0
(145)
Ph.D. in Biochemistry--University Professor--Chemistry Tutor
If you take the average calorie content of protein and carbohydrates as 4 calories/g and that of fat as 9 calories/g, then..
15 g protein x 4 cal/g = 60 cal
1.0 g fat x 9 cal/g = 9 cal
42 g carb x 4 cal/g = 168 cal
Total calories = 60 + 9 + 168 = 237 calories
237 cal x 1 kcal/1000 cal = 0.237 kcal
Answer to 2 significant figures would thus be 0.24 kcal
Sorry I made an error of multiplication the first time.
Arturo O.
The line in the answer that says "42 g carb x 4 cal/g = 84 cal" should be "42 g carb x 4 cal/g = 168 cal", which changes the final answer to 237 cal.
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05/17/17
Amad A.
thank you
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05/17/17
Ken G.
Do you always multiply the fats by 9?
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08/28/18
J.R. S.
tutor
If you accept the idea that every 1 g of fat contributes 9 calories, then YES you would always multiply the number of grams of fat by 9 to get calories.
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08/28/18
Mir B.
how do you know to multiply the fats by 9 and the proteins and carbs by 4?
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12/27/18
Amad A.
05/17/17