Question 143218
You won't be able to derive a specific answer, because you have three variables and only two defined relatiionships.


Cost of standard: x
Cost of double: y
Cost of suite: z


Average of the 3 is 140, so {{{(x+y+z)/3=140}}}


Average of standard and suite is 135, so {{{(x+z)/2=135}}}


So you can say that {{{x+y+z=420}}} and {{{x+z=270}}}.


So {{{x=270-z}}}


Substituting:


{{{270-z+y+z=420}}} which is to say {{{y=150}}}, so we know the price of a double, but as for the standard and suite, all you know is that they add up to 270.  The standard could be $1 and the suite $269, or the standard could be $90 and the suite $180 -- or any other combination that totals 270.  So all you can say for sure about the cost of the suite is that it is $270 minus the cost of the standard -- whatever it is.


From a practical point of view, you would expect the suite to be greater than $150.  After all, who would then book a double room if you could get the suite for the same money?  By the same logic, the standard room must be less than $120 otherwise the suite could not be greater than $150.


So, for the suite, the cost must be an element of the set of all z such that z * 100 is an integer (can't make change smaller than a penny), 150 < z << 270.  (<< means 'a lot less than').  z has to be 'a lot less than' 270, otherwise the hotel would be charging too little for the standard rooms.