Bunuel
If x ≤ 4 and y ≥ 10, what is the range of the numbers in the set {5, 8, x, y}?
(1) 3x + 5y = 72
(2) –7x + 7y = 56
Hi,
a good Q...
as can be seen from the restrictions in the upper limit of x as 4 and lower limit of y as 10, the range would depend on the values of x and y only......
lets see the statements...
(1) 3x + 5y = 72
since y is the bigger number, lets substitue y as 10, then 11, 12,13... and find if there is any integer value fitting in for x..
let y=10.. 3x+5*10=72... 3x=22.... x cannot be integer..
let y=11... 3x+5*11=72...3x=17...x again cannot be integer
let y=12.. 3x+5*12=72... 3x=12.... x =4.. so x,y can be 4,12and we get one set of answer..range=8
let y=13... 3x+5*13=72...3x=7...x again cannot be integer
let y=14... 3x+5*14=72...3x=2...x again cannot be integer
let y=15.. 3x+5*15=72... 3x=-3.... x =-1.. so x,y can be -1,15 and we get another set of answer..range=16
no need to look forward.. we have more than one range so insuff.
(2) –7x + 7y = 56
7(y-x)=56..
y-x=8..
suff as it gives us the range as 8 irrespective of values of x and y
x,y can be 2,10...3,11...4,12 and n
ans B
Why is it important for x and y to only be integers? I am confused since its not mentioned in the question and Range can be of non-integer values also right?