If x and y are nonnegative integers and x + y = 25, what is x?
(1) 20x + lOy < 300
(2) 20x + lOy> 280
statement 1
20x+10y<300
=2x+Y<30
=2x+y<25+5
=2x+y<x+y+5
=x<5
insufficient
statement 2
20x+10y>280
=2x+Y>28
=2x+y>25+3
=2x+y>x+y+3
=x>3
insufficient
together we get 3<x<5.so x must be 4
so answer is c
is my approach ok?
mgmat
This topic has expert replies
-
- Master | Next Rank: 500 Posts
- Posts: 226
- Joined: Thu Nov 25, 2010 12:19 am
- Thanked: 3 times
- Followed by:2 members
- Geva@EconomistGMAT
- GMAT Instructor
- Posts: 905
- Joined: Sun Sep 12, 2010 1:38 am
- Thanked: 378 times
- Followed by:123 members
- GMAT Score:760
It's good. Would just like to point out that you can also isolate (x+y) on the left side of the inequality and substitute that for 25, instead of isolating 25 on the right and substituting that for x+y.nafiul9090 wrote:If x and y are nonnegative integers and x + y = 25, what is x?
(1) 20x + lOy < 300
(2) 20x + lOy> 280
statement 1
20x+10y<300
=2x+Y<30
=2x+y<25+5
=2x+y<x+y+5
=x<5
insufficient
statement 2
20x+10y>280
=2x+Y>28
=2x+y>25+3
=2x+y>x+y+3
=x>3
insufficient
together we get 3<x<5.so x must be 4
so answer is c
is my approach ok?
For example:
Stat. (1)
20x+10y<300
=2x+Y<30
=x+x+y<30
=x+25<30
=x<5