15. At a constant temperature (T), the volume (V) of a gas varies inversely as the pressure (P). If the pressure of a certain gas is 40 N/m2 when the volume is 600 m3 what will the pressure be when the
volume is reduced to 320 m3?

the direct variation says that:

then the equation is of the form is given by:

            where k is the constant variation.

from the given table:

consider any value of x and m(x)=y

x = 2 and m(x)=y = 3

substitute these value in [1]; we have;

divide both sides by 2 we get;

⇒

check:

put x = -1 and m(x) = -1.5

substitute in the equation:

-1.5 = -1.5                   true

therefore, the function m(x) represents a direct variation

graph of this function as shown below: