Source: Official Guide for the GMAT 13th Ed. Problem Solving; #55 Official Guide for the GMAT 2015 14th Ed. Problem Solving; #55

2

In the table above, what is the

In the table above, what is the number of green marbles in Jar R?

3 Explanations

2

MANSUR I OMAR

(x+y)+(y+z)+(x+z) = 80+120+160
2x+2y+2z = 360
x+y+z= 180

Now,
(x+y+z) - (x+y) = 180 - 80
z = 100

So, we found 100 green balls in jar R (Ans:D)

Oct 16, 2016 • Comment

Sam Kinsman, Magoosh Tutor

Yes, that approach works as well! Good job Mansuri :)

Oct 17, 2016 • Reply

1

X + Y = 80
Y + Z = 120
X + Z = 160

Value we want to obtain: Z

Equations in which Z is present:

Y + Z = 120
X + Z = 160

Equations in which Z is NOT present:

X + Y = 80

Both variables (X and Y) are present in equations which hold Z as a second variable.

Let´s substitute both terms and write them in term of Z, thanks to the equations which do have Z as a variable.

X + Y = 80

(160 - Z) + (120 - Z) = 80

160 + 120 -2Z = 80
-2Z = 80 - 280
-2Z = -200
Z = 100

Correct Answer = 100 (D)

Jan 25, 2015 • Comment

2

Gravatar Mike McGarry, Magoosh Tutor

Dec 27, 2013 • Comment

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