Are any of you good at math?

[MVP]

I was taking the ACE practice exam earlier and came across a couple of problems above my math solving ability, I know there's going to be similar problems like these so I was curious if any of you knew the formula.

The first problem was like this:

1) Fred is 193lbs and has 157lbs of lean body mass, what is his bodyfat%?

The second one was like this:

2) Using the food label provided, calculate the percentage of the product's calories that are from carbohydrate.

Nutrition Facts
Serving size 3 crackers (16g)
Servings per container: about 16

Amount per serving:
Calories: 80 | Calories from fat: 30

Total Fat: 3.5g
Saturated fat: 2g
Cholesterol: 0mg
Sodium: 160mg
Total carbohydrate: 10g
Dietary Fiber: 1g
Sugars: 1g
Protein: 2g

Thanks.

[Aoife]

so if he has 157 pounds of lean mass, he has 193-157 pounds of fat, right? and then to find percentage you would divide the amount of fat by the whole weight.

how many calories is a gram of carbs? multiply that by the number of carbs (total) and and again, divide it by the total amount of cals.

[MVP]

For the bodyfat, weight (193) minus lean mass (157) = 36 divided by weight (193) = 18.65%


For the second, calories (80) minus total carb calories (10g at 4 calories per gram =40 calories) divided by total calories so 80 minus 40 calories from carbs divided by total calories equals .5 or 50%

^ so those would be accurate formulas?

[Aoife]

you woudn't subtract carb cals from total cals. just divide carb cals by total cals. but otherwise, yes.

[MVP]

Thanks, just to make sure I got it I wrote down another equation on wordpad.

Mark is 202lbs and his LBM is 170lbs

What is his bodyfat%?

My answer:- 18.8%

Calories: 140
Carbohydrates: 30g

30 X = 120 / 140 = 80%

Did I do those right?

Thanks again.

[LisaS]

No (unless you made typos). Are you using a calculator?

202 total. 170 LBM. By subtraction, this means 32 FAT. (202 - 170)
Set up your word problem like this:
Part out of Total is what?
Part/Total = X
so:
32 out of 202 is what?
32/202 = X
32/202 = 0.158 or 15.8%

30g CHO * 4 cal/g = 120 cals
120 out of 140 is what ?
120/140 = ?
120/140 = 0.857 or 85.7%

[MVP]

Thanks Lisa. I believe I divided his LBM and his fat. I should have divided his fat by his total weight like you did which equals 15.8%

The 2nd equation I got the same thing you did @ 0.857 but forgot to round, so it would equal moving the decimal two places and that's the percentage? 85.7%?

Thanks!

[LisaS]

Take the decimal number * 100 to get percentage and then drop decimals if you need to. Don't see 0.857 and pick either 0.9 and say 90% or 0.8 and say 80% - neither is correct in this set up.

85.7 doesn't round to 80% ever.

If you need to drop the decimal, take it up to 86% (since you are over .5)

If it is a multiple choice test, this is where they will get you.
They probably would have offered both 18.8 and 15.8 as valid answers (since it would be a common mistake) and then since you saw one that matched you'd pick it.

Since fat is 9 cals per gram and CHO & PRO are 4 cal per gram - they'll have a choice that is the solution if you use the wrong conversion factor.

[MVP]

Yeah I know.

So if a box of oreos contain 213 calories and the carbs are 40 and they ask for the percentage of calories from carbs I would just simply go...

40 X 4 = 160 / 213 = 75%

I think I got it, thanks for the help!

[LisaS]

Yup.

How about this one. Bob weighs 235. He is 23.5% Fat. What is his LBM?

Or
One scoop wonderpowder has 12g protein, no carb, no fat. How many even (no partial) scoops can you have and stay under 200 calories? How much protein would that be?

[MVP]

Thanks for the equations.

Bob's LBM is 180lbs (rounded).

Is it 4 scoops?

[PlankIt]

Originally Posted by MVP

Thanks for the equations.

Bob's LBM is 180lbs (rounded).

Is it 4 scoops?

Yes

[MVP]

Alright so I think I'm on a roll, I take the ACE exam August 8th. So far, I'm reading a chapter per day and going over the flash cards, I'm pretty confident I'll pass but I'm spending a lot of time studying.

These little math equations are simple once you understand the formulas, I just didn't want to sacrifice problems over simple math work.

I can answer correctly every single flash card that came with the ACE manual, hopefully that's an indicator that I can take the test and pass it!

[EasyRhino]

I'm pretty sure the answers are:

1) Fred is a lardass, he should get in the gym and squat.

2) You'll never get hyooge eating crackers, smash the package into the client's face, and tell them to drop and give you twenty.

[MVP]

LMAO! That's pretty funny man.

I just found out the test is done without a calculator and I suck at division!

[LisaS]

hopefully then they'll give you easy math that you can do in your head like the carbs in your first example.
or a 200 lb man with 30lb of fat.

[MVP]

Well from what the ACE site said - it's multiple choice. So if my math problem I do on paper doesn't equal one of the answers I'll know I did something wrong.

Thanks for the help though, you guys have been extremely helpful, especially you Lisa