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Math Help - Help an old lady please

  1. #1
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    Help an old lady please

    Hi everyone. Its been a VERY long time since i have taken math and now im in need of help. Taking a Anatomy Lab class and need some direction on how to complete my lab assignment. Im not sure im in the right section, If this needs to be moved let me know
    Thanks in advance

    I did a bunch of tests with rats.. NOW I have more questions to answer but have to do the math first

    Determine the oxygen consumption per hour for the rat. Use the following formula

    Ml O2 consumed 60 minutes
    ____________ x _________ = ml O2/hr I cant get these boxes straight, I hope you understand
    1 Minute 1 Hour


    The first rat used 7.0 ml in 1 min according to my test, SO that would go on the top left line. NOW WHAT????


    AND then after you get that answer….then I need to do this.

    Now that you have the amount of Oxygen used per hour, determine the metabolic rate per kilogram of body weight using the following formula (note that you will need to convert the weight data from g to kg before you use the formula)

    Metabolic rate = ml O2/hr
    ____________ = ml O2/kg/hr

    Wt.in kg

    The first rates weight was 249.3 grams


    Please explain how you get the answer i have about 20 more just like this one to do
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  2. #2
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    Hello lasalp

    Welcome to Math Help Forum!

    The important thing here is not to panic at the sight of what looks like a complicated formula, but to use some common sense. The first formula you've quoted is
    Quote Originally Posted by lasalp View Post

    Determine the oxygen consumption per hour for the rat. Use the following formula

    Ml O2 consumed 60 minutes
    ____________ x _________ = ml O2/hr I cant get these boxes straight, I hope you understand
    1 Minute 1 Hour


    The first rat used 7.0 ml in 1 min according to my test, SO that would go on the top left line. NOW WHAT????
    This formula is simply saying that however much oxygen the rat consumed in one minute, it will consume 60 times as much in an hour. That's pretty obvious, isn't it? This rat consumed 7.0 ml in 1 minute, so it will consume 7.0 x 60 = 420 ml in an hour.

    The next bit is in two parts:
    ... convert the weight data from g to kg
    which you can do by dividing the weight in grams by 1000, since there are 1000 g in 1 kg.

    The first rat's weight was 249.3 g. So in kg, this is 249.3 \div 1000 = 0.2493.

    ...and then
    use the formula

    Metabolic rate = ml O2/hr
    ____________ = ml O2/kg/hr

    Wt.in kg
    This just says to divide the oxygen consumption per hour that we just worked out, by the rat's weight in kg. So that's 420 \div 0.2493, which according to my calculator is 1684.7, to 1 d.p.

    That didn't hurt, did it?

    Grandad
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    Thank you SOOO Much, you were very helpful... I only have one question...
    This was your answer to the problem

    1684.7, to 1 d.p.

    Where did the 1 d.p come from? Would you mid if i thru out one more(with the answer) and see if i did it right?

    Sandy
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  4. #4
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    A New problem using the same formula

    NEW PROBLEM SAME Formula
    Quote:
    Originally Posted by lasalp

    Determine the oxygen consumption per hour for the rat. Use the following formula

    Ml O2 consumed 60 minutes
    ____________ x _________ = ml O2/hr I cant get these boxes straight, I hope you understand
    1 Minute 1 Hour


    The first rat used 7.8 ml in 1 min according to my test, SO that would go on the top left line. NOW WHAT????


    This formula is simply saying that however much oxygen the rat consumed in one minute, it will consume 60 times as much in an hour. That's pretty obvious, isn't it? This rat consumed 7.8 ml in 1 minute, so it will consume 7.8 x 60 = 468ml in an hour.

    The next bit is in two parts:
    Quote:
    ... convert the weight data from g to kg
    which you can do by dividing the weight in grams by 1000, since there are 1000 g in 1 kg.

    The first rat's weight was 250.6 g. So in kg, this is 250.6 1000 = 0.2506

    ...and then
    Quote:
    use the formula

    Metabolic rate = ml O2/hr
    ____________ = ml O2/kg/hr

    Wt.in kg
    This just says to divide the oxygen consumption per hour that we just worked out, by the rat's weight in kg. So that's 468 0.2506, which according to my calculator is 1867.51(and a bunch of other numbers after that?)

    Does this look right?

    Sandy
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  5. #5
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    Hello Sandy

    Your second calculation is fine.

    As far as the '1 d.p.' is concerned in the first example, it's just that, whenever you do a calculation using a calculator and the answer isn't exact, you'll always need to 'round off' in some way. I just chose 1 d.p. as a fairly sensible place to stop. I could have given the answer to the nearest whole number, in which case it would have been 1685. (Can you see why it's 1685 and not 1684? It's because the bit after the d.p. is more than half-way to the next number.)

    In your answer to the second question, you stopped after 2 d.p. and wrote down 1867.51. In fact, correct to 2 d.p., the answer should be 1867.52 - again because the bit that you've left out is more than half-way to the next number. If you rounded this answer to 1 d.p., it would be 1867.5; and to the nearest whole number it would be 1868. OK?

    Grandad
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  6. #6
    Super Member Matt Westwood's Avatar
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    Quote Originally Posted by lasalp View Post
    Thank you SOOO Much, you were very helpful... I only have one question...
    This was your answer to the problem

    1684.7, to 1 d.p.

    Where did the 1 d.p come from? Would you mid if i thru out one more(with the answer) and see if i did it right?

    Sandy
    Just in case you're confused: "d.p." = "decimal place". Feel free to give us a stern talking-to when we fail to recognise that we use unexplained abbreviations ...
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