Aperson's eardrum has an area of
0.000200 m^2. how much force
does the outside air, at 1.00 atm,
exert on the eardrum?

Since we have

where P is the pression, F is the force and S is the surface, we can solve the formula for the force as follows

In order to have consistent units of measure, we convert

and we plug the values:

there is only one way to arrange all the eight relative to each other because they are not distinct. we have

now there are nine places to place an (and not more than one in one place).   because we have four symbols, we need to choose four of these nine places to insert an . order does not matter because the are not distinct.

thus there are 1 · c(9,4) ways, or, if we calculate it,

thus there are 126 ways to form such "words."