Couple GMAT Prep Questions

Hi David,
These questions are testing your basic knowledge of LCM and word translation.
Lets take one by one:

Q1. Camera in 1993 = a
Camera in 1994 = x % of 1993 more
= a + (x/100)a
= a(1 + x/100)
Now in 1995 = y% of 1994 more than 1994
= y/100*a(1 + x/100) + a(1 + x/100)
= (a/100)[y + xy/100 + x/100 +1]
= (a/100)[1 + x+ y + xy/100 ]

We already know a = 1000 so we need to know the value of this expression [1 + x+ y + xy/100 ]
Now look at the statements

1. xy = 20 Donno what is x? Donno what is y? Hence INSUFFICIENT. Eliminate A,D

2. [1 + x+ y + xy/100 ] = 9.2 Hence SUFFICIENT

Ans B


Second Question
Q2. Given x>0 y>0 and what is y in x/y
So effectively you need the value of either this fraction or you need both x and y. look at the statements

1. LCM of X/Y and 1/3 is 6

Now recall LCM is written by taking the maximum powers of the primary factors of the twon numbers
So if LCM of Y and 3 is 6 => either Y = 6 or Y=2
Two values of Y hence INSUFFICIENT Eliminate A,D

2. x=1 Donno what is Y hence INSUFFICIENT elimate B

Now taking both together:
X= 1
Y = 2,6
INSUFFICIENT Eliminate C

Hence the answer is E.

Let me know if it helps

Thanks
Komal

joshi.komal, in the first question you have a formula:

(a/100)[1 + x+ y + xy/100 ]

and you know that xy=20 so x=20/y so you get this:

(1000/100)[1 + 20/y+ y + 20/100 ]

If the answer is B, where am I going wrong?

xilef wrote:joshi.komal, in the first question you have a formula:

(a/100)[1 + x+ y + xy/100 ]

and you know that xy=20 so x=20/y so you get this:

(1000/100)[1 + 20/y+ y + 20/100 ]

If the answer is B, where am I going wrong?

You don't know the value of y. There is still one variable(y) without any value so the choice is INSUFFICIENT.

Thanks
Komal

thanks.