How Many Influenza Viruses Land on You from a Cough?

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The discussion centers on calculating the number of influenza viruses that land on a person from a cough, using the volume of saliva and the size of the virus. The influenza A virus has a diameter of 85 nm, and the volume of saliva is given as 0.010 cm³, with 1/10^9 of that volume containing viral particles. The initial calculations suggest using the formula for the volume of a sphere to determine the volume of a single virus. There is a clarification needed on whether to divide the virus volume by the saliva volume or vice versa, and considerations regarding the spherical nature of both the virus and the saliva are mentioned. The discussion emphasizes the importance of understanding the teacher's expectations for the calculation method.
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Homework Statement


A typical virus is a packet of protein and DNA (or RNA) and can be spherical in shape. The influenza A virus is a spherical virus that has a diameter of 85 nm. If the volume of saliva coughed onto you by your "friend" with the flu is 0.010 cm3 and 1/109 of that volume consists of viral particles, how many influenza viruses have just landed on you?


Homework Equations


V = 4/3 x pie x r^3


The Attempt at a Solution


I'm thinking that I should take half of 85nm which is 42.5nm and plugging it into the volume formula for a spherical. The volume of the whole spherical virus comes out to be 3.21E-5.

3.21E-5 / 0.010cm^3 = .00321

1/10^9 of .00321 = 3.11E-7 particles?
 
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Its easier if you use nanometers in the original volume calculation. Secondly you would not divide the virus volume by the saliva volume, you need to do this the other way round. Thirdly I don't know if they want you take the spherical nature of the virus into account and assume spherical saliva which could make a big difference. You'll know what your teacher wants more than me.
 

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