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The blood that circulates in our body is about 1/12 of our mass. If the kidneys filter 7.5 liter of blood a hour, then how many times does it filter in the kidney the whole blood of a person will mass 60kg?

Here's what my teacher did:

1/12*60=5 liter blood

0.55*5=2.75 liter plasma of blood.

The plasma is filtered 60 times is 24 hours. (how did she find that?)

24 hours ->60 times the plasma filters

1 hour -> x

x=2.5 times

Do you understand her explanation? What should I do next?

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  • $\begingroup$ Could you please explain a bit better what the question of the exercise is? $\endgroup$
    – FloriOn
    Feb 3 '16 at 15:31
  • $\begingroup$ This is what is written in my book. I don't understand either if it says find how many times the blood filters in a day or hour. $\endgroup$
    – prishila
    Feb 3 '16 at 16:33
  • $\begingroup$ @prishila, If you feel that my answer was correct or helpful, please vote up or accept it (click on the hollow check mark you see below the voting buttons). Thanks :) $\endgroup$
    – Thawn
    Feb 10 '16 at 13:52
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I'll try to dissect your teachers answer for you:

1/12*60=5 liter blood

no explanation required here

0.55*5=2.75 liter plasma of blood.

only the plasma is filtered in the kidney (the 45% cell content remains in the blood stream), so out of the 5 l blood, only 2.75 l need to be filtered.

The plasma is filtered 60 times is 24 hours. (how did she find that?)

the kidney filteres 7.5 l per hour so if the whole blood plasma has 2.75 l, then in one hour the whole blood is filtered 7.5/2.75=2.73 times. In one day the whole blood is filtered 2.73*24=65.5 times (the numbers are slightly rounded).

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