T1101
If the average (arithmetic mean) of the three different positive integers x,y and z is 3, what is the median of the three integers?
(1) x=5
(2) y=3
Answer:
Given that the average of three numbers is 3.
1) since x= 5, this means other two numbers must be less than 5 (because mean of xyz is 3, hence there sum must be 9, so if x =5, =>. y+z = 4, so neither y nor z can be greater than 5, also 4)
Lets try to find out what will be our second largest number (lets say y).
Can Y be 4?, No since y+z must be equal to 4 and both y and z must be positive
Can Y be 3? Yes, since for y=3, we can have z=1 and y+z will be equal to 4. ALSO WITH THIS WE HAVE OUR MEDIAN AS 3.
Can Y be 2? No, because then for having y+z = 4, z must be 2 which can not be true as all three numbers must be different.
so we can only have cases with either Y=3 and Z=1 (as shown) or vice-versa. In any of the two case, MEDIAN WILL BE 3. So option 1 is sufficient.
2) For y=3 and mean of X,Y,Z = 3, Y must be at the center. Why?
because if X and Z will be greater than Y, the 3 CANT BE THE MEAN ( as y=3 will be smallest). Sim, will be the case wit X,Z lower than Y.
Hence Y must be in the middle . This is also sufficient.
so both conditions are sufficient. Hence choice D is right