zarahh09
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I am so bad at maths, someone please please help

1. Calculate the volume of a lumen that measures 30mm in length and 12mm in diameter in mm^3.

2. Calculate the maximum volume of blood in dm^3 that can be expelled every hour from a left ventricle with a volume of 75cm^3 and a heart rate it 66 beats per min
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BDavies1
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(Original post by zarahh09)
I am so bad at maths, someone please please help

1. Calculate the volume of a lumen that measures 30mm in length and 12mm in diameter in mm^3.

2. Calculate the maximum volume of blood in dm^3 that can be expelled every hour from a left ventricle with a volume of 75cm^3 and a heart rate it 66 beats per min
1. The blood vessel will be a cylinder so you would use the formula for the volume of a cylinder:

Volume = pi x radius squared x length (pi =3.14)
Radius = half of the diameter, which in this case is 30/2 =15 mm, so radius squared is 15 x 15 = 225
Put the numbers in and work out the volume. The units of volume will be in mm^3

2. Volume of blood pumped (in 1 hour) = volume of one beat x no of beats in 1 hour
the volume of one beat is 75 cm3

There are 66 beats per minute, so no of beats in 1 hour = 66 x 60

Put the numbers in and that will give you volume in cm3
Then you need to work out the volume in dm3 by dividing by 1000 (there are 100 cm3 in 1 dm3)
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zarahh09
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(Original post by BDavies1)
1. The blood vessel will be a cylinder so you would use the formula for the volume of a cylinder:

Volume = pi x radius squared x length (pi =3.14)
Radius = half of the diameter, which in this case is 30/2 =15 mm, so radius squared is 15 x 15 = 225
Put the numbers in and work out the volume. The units of volume will be in mm^3

2. Volume of blood pumped (in 1 hour) = volume of one beat x no of beats in 1 hour
the volume of one beat is 75 cm3

There are 66 beats per minute, so no of beats in 1 hour = 66 x 60

Put the numbers in and that will give you volume in cm3
Then you need to work out the volume in dm3 by dividing by 1000 (there are 100 cm3 in 1 dm3)
Is the first answer : 3392.92
Second: 297
Last edited by zarahh09; 7 months ago
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BDavies1
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(Original post by zarahh09)
Is the first answer : 3392.92
Second: 297
1. The first answer is wrong but that's because I was careless and said the diameter was 30 mm and it is not, it is 12- but your answer would be correct,
2. Well done this is correct

Who said you couldn't do maths !??
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susiebe
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'Then you need to work out the volume in dm3 by dividing by 1000 (there are 100 cm3 in 1 dm3)'

Wouldn't you therefore divide by 100?
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ari1224
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(Original post by susiebe)
'Then you need to work out the volume in dm3 by dividing by 1000 (there are 100 cm3 in 1 dm3)'

Wouldn't you therefore divide by 100?
It's a mistake there is 1000cm3 in 1 dm3
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Davies Chemistry
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(Original post by susiebe)
'Then you need to work out the volume in dm3 by dividing by 1000 (there are 100 cm3 in 1 dm3)'

Wouldn't you therefore divide by 100?
1000cm3 in 1 dm3 ..divide by 1000
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