Question

There are 130 calories in a cup of whole milk and only 86 in a cup of skim milk. In switching to skim milk, find the percent decrease in number of calories.

Answer 1

if you say hmmm are drinking whole milk, then you switch to skim...hmmm so we can say that the whole milk of 130 calories is the 100%, then now it dropped to 86? what the? so.. it dropped by 130-86, that's how much it dropped in calories, how much is that in percentage from 130?

well
`\bf \begin{array}{ccllll} amount&\%\\ \textendash\textendash\textendash\textendash\textendash\textendash&\textendash\textendash\textendash\textendash\textendash\textendash\\ 130&100\\ 130-86&x \end{array}\implies \cfrac{130}{130-86}=\cfrac{100}{x}`

solve for "x"

Answer 2

Answer: The required percent decrease in the number of calories is 33.85%.

Step-by-step explanation: Given that there are 130 calories in a cup of whole milk and only 86 calories in a cup of skim milk.

We are to find the percent decrease in number of calories in switching to skim milk.

The decrease in the number of calories in switching to skim milk is

`n_d=130-86=44~\textup{calories}.`

Since the number of calories in a cup of whole milk is 130, so the percent decrease in the number of calories is

`p\\\\\\=(n_d)/(130)*100\%\\\\\\=(44)/(130)*100\%\\\\\\=(22)/(65)*100\%\\\\=33.85\%.`

Thus, the required percent decrease in the number of calories is 33.85%.