Be Careful!!

1) If m > 0, y > 0, and x is m percent of 2y, then, in terms of y, m is what percent of x?

2) A certain NYC taxi driver has decided to start charging a rate of r cents per person per mile. How much, in dollars, would it cost 3 people to travel x miles if he decides to give them a 50% discount?

3)What is the ratio of the surface area of a cube to the surface area of a rectangular solid identical to the cube in all ways except that its length has been doubled?

4)A certain square is to be drawn on a coordinate plane. One of the vertices must be on the origin, and the square is to have an area of 100. If all coordinates of the vertices must be integers, how many different ways can this square be drawn?

5) Is z even?

(1) z/2 is even.

(2) 3z is even.

muzali wrote:

1) If m > 0, y > 0, and x is m percent of 2y, then, in terms of y, m is what percent of x?

x=(m/100)*2y=2ym/100=ym/50

m=Z percent of x, we need to find Z

Z=m*100/x=m*100/(ym/50)=5000/y

Good! People usually forget the % ( 100)

muzali wrote:

2) A certain NYC taxi driver has decided to start charging a rate of r cents per person per mile. How much, in dollars, would it cost 3 people to travel x miles if he decides to give them a 50% discount?

r cents per person per mile
=>(r/100) $ per person per mile
=> (3r/100) $ for 3 people per mile
=> (3xr/100) $ for 3 people for x miles
=> (3xr/200) $ for 3 people for x miles with 50% discount

Good! 1dolar=100 cents - you can miss this detail in hurry!

muzali wrote:

3)What is the ratio of the surface area of a cube to the surface area of a rectangular solid identical to the cube in all ways except that its length has been doubled?

Surface area of cube with side a= 6a*a
Surface area of cuboid with one side 2a= 2(a*a+a*2a+a*2a)=10a*a
Desired ratio=6/10=3/5

Well done

muzali wrote:

4)A certain square is to be drawn on a coordinate plane. One of the vertices must be on the origin, and the square is to have an area of 100. If all coordinates of the vertices must be integers, how many different ways can this square be drawn?

4 squares can be drawn using the +x,+y; +x,-y; -x,-y and -x,+y where the absolute values of x and y are 10 to have area of 10*10 =100
4 other squares can be drwn by using the diagonals between the axes.

Total number = 4+4 =8

In Quarter 1: You can have (0,10), (6,8), (8,6) and (10,0)

For the 4 Quarters : 4x4 = 16

4 will be overlap. So 16-4 = 12

This one was trick!! BE CAREFUL

muzali wrote:

5) Is z even?

(1) z/2 is even.

(2) 3z is even.

(1) z/2 is even => z=even*2 = even =>sufficient
(2) 3z is even
odd*even =even, 3 is odd , so z has ro be even =>sufficient

Answer = D

3z = EVEN but nothing in question stems says Z is an integer so Statement two is INSUF.

Hence , A

BE CAREFUL!

msd_2008 wrote:Logitech,

I am somehow not convinced with the 5th answer i.e Is Z even?
You mentioned that it should be A and not D because it is nowhere given that Z is an integer.
Well, if 3Z is even then Z has to be even because 3 is odd. And why do we need the information about Z being an integer here? Can you illustrate any fraction which when mutliplied by 3 gives u an even product?

Regards
MSD