A very, very basic math question!

[WorkingTheDoors]

I know this is a basic math question, guys - but its got me baffled! (I guess I'm a bouncer for a reason!)

I'm looking at chicken on a website that I'd like to purchase, however, I just need a formula on how to calculate the protein in it.

For example:
Per 100g of chicken has 27.8g of protein, however, I don't need this amount - I only want to get 21g of protein from it.. whats the formula?

I'm thinking its .278 x 100 = 27.8, so I've been going down numbers and I got to .278 x 79 = 21.something. Is this right?
If so, there must be a quicker way to locate how many gram of the chicken I'll need to get 21g of protein from it? Surely?

Also, if it is right - why doesn't the same formula for the fat content work?

Per 100g of this same chicken has 1g of fat. Therefore, 0.1g x 79 (same as above) = 7.9.

I know this can't be right because if 100g contains 1g of fat, then how can a less amount of chicken contain more fat?


Baffled! Any answers with formulas please?

 

[Yogi]

.278*x = 21
x = 21/.278
x = 75.54g

1g of fat per 100g = .01 not .1

.01*75.54 = .7554g fat

 

[WorkingTheDoors]

.278*x = 21
x = 21/.278
x = 75.54g

1g of fat per 100g = .01 not .1

.01*75.54 = .7554g fat

So..

100g Chicken = 27.8g protein.
Goal = To get 21g protein from it.
21(goal)/27.8(whats in it) = 0.755
0.755 x 100g = 75.5g
75.5g = 21g protein.

Is that right?

If so, what would the forumla be to get a surplus of ingredients within something such as.. oatmeal?

For example: 100g of oatmeal contains 60g carbs, I need 103.6 carbs, what would the forumla be?

Thanks in advance man.

 

[Yogi]

So..

100g Chicken = 27.8g protein.
Goal = To get 21g protein from it.
21(goal)/27.8(whats in it) = 0.755
0.755 x 100g = 75.5g
75.5g = 21g protein.

Is that right?

If so, what would the forumla be to get a surplus of ingredients within something such as.. oatmeal?

For example: 100g of oatmeal contains 60g carbs, I need 103.6 carbs, what would the forumla be?

Thanks in advance man.

oatmeal : protein
100g : 60g
x : x(this is just a multiplier to get from row 1 to row 3)
? : 103.6g

60 * x = 103.6 (reading down the 2nd column)
\(\displaystyle \frac{60*x}{60}=\frac{103.6}{60}\) Divide by 60 on both sides to get x by itself
x = 103.6/60 = 1.7267

Now we know x, the multiplier to get from row 1 to row 3:
100 * x = ? (reading down the 1st column)
100 * 1.7267 = 172.67

172.67 : 103.6

 

[WorkingTheDoors]

oatmeal : protein
100g : 60g
x : x(this is just a multiplier to get from row 1 to row 3)
? : 103.6g

60 * x = 103.6 (reading down the 2nd column)
\(\displaystyle \frac{60*x}{60}=\frac{103.6}{60}\) Divide by 60 on both sides to get x by itself
x = 103.6/60 = 1.7267

Now we know x, the multiplier to get from row 1 to row 3:
100 * x = ? (reading down the 1st column)
100 * 1.7267 = 172.67

172.67 : 103.6

Thanks again for the continuous replies.

Would I be correct in saying this is the formula laid out in a simpler notion:

100g oats = 60g carbs
103.6/60 (carbs i want) = 1.7267
Now times the original 100g by 1.7267 and we get 172.67grams of oatmeal I'd need to get 103.6 carbs?

 

[Yogi]

You are right but I'll try to keep it more simple than the last post.

oatmeal:carbs
100g : 60g [We want the right to be 103.6...]
(103.6/60)100 : 60(103.6/60) [...so here we force it to be so]
172.67 : 103.6