Question

Calculate the number of calories present in a chocolate chip cookie that contains 16 g carbohydrate, 3 g protein, and 7 g fat. Express your answer to one significant figure and include the appropriate units.

Answer 1

As per USDA site, these are the calories aporte by type of nutrient:

Fat: 9 cal / g
Protein: 4 cal / g
Carbohydrates: 4 cal / g

Then,

16 g Carb. * 4 cal / g = 64 cal
3 g protein * 4 cal / g = 12 cal
7 g fat * 9 cal / g = 63 cal
---------------- -----------
26 g 139 cal

Rounded to one significant figure 100 cal.

Answer: 100 cal.