VIC Problem

[jbigs]

I thought this problem was fairly straight forward but I got the question wrong. When I went back and tried the question again, I got the same answer. I checked the solution that was provided, but I am confused about the units of cents and dollars in the question. Can someone tell my why answer D is correct and not A?

Here is the question and answer choices (I also have included my methodology):

"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?"

Answer Choices

(a) (3xr)/2

(d) (3xr)/200

My Methodology (Ihave used many different numbers but I am going to use the MGMAT here):

r= number of cents per mile per person
x= number of miles the taxi will travel

r=10 cents per person per mile
x= 20 miles

Trip cost= (3 people)*(10 cents per person per mile)*(20 miles)=600 cents

Apply 50% discount and the trip cost=300 cents

Now, I plug r=10 and x=20 into the answer choices

(a) (3*10*20)/2 = 600/2 =300 cents (seems to match my answer of 300 cents and I choose this one but get it wrong)

(d) (3*10*20)/200 = 600/200 = 3 cents (this is the correct answer on the sample test)

Can someone help me to understand this question?

Best,

John

[TheChakra]

I thought this problem was fairly straight forward but I got the question wrong. When I went back and tried the question again, I got the same answer. I checked the solution that was provided, but I am confused about the units of cents and dollars in the question. Can someone tell my why answer D is correct and not A?

Here is the question and answer choices (I also have included my methodology):

"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?"

Answer Choices

(a) (3xr)/2

(d) (3xr)/200

My Methodology (Ihave used many different numbers but I am going to use the MGMAT here):

r= number of cents per mile per person
x= number of miles the taxi will travel

r=10 cents per person per mile
x= 20 miles

Trip cost= (3 people)*(10 cents per person per mile)*(20 miles)=600 cents

Apply 50% discount and the trip cost=300 cents

Now, I plug r=10 and x=20 into the answer choices

(a) (3*10*20)/2 = 600/2 =300 cents (seems to match my answer of 300 cents and I choose this one but get it wrong)

(d) (3*10*20)/200 = 600/200 = 3 cents (this is the correct answer on the sample test)

Can someone help me to understand this question?

Best,

John

The answers are given in Dollars so you cannot make the substitution directly. Convert 10 cents to .1 dollar and the answers will match.

[jbigs]

Thank you.

[StaceyKoprince]

yep - do make sure you check the units given in the problem vs. the units used in the answers! Also, on a slightly different but related topic, a GMAC rep said at a conference a couple of weeks ago that they will start moving away from using US currency without giving the conversion rates so that international students won't automatically be expected to know the US currency system. If they give you the conversion (eg 100 cents = 1 dollar) then that will be an extra clue to you that you'll have to convert at some point.

[rustom.hakimiyan]

yep - do make sure you check the units given in the problem vs. the units used in the answers! Also, on a slightly different but related topic, a GMAC rep said at a conference a couple of weeks ago that they will start moving away from using US currency without giving the conversion rates so that international students won't automatically be expected to know the US currency system. If they give you the conversion (eg 100 cents = 1 dollar) then that will be an extra clue to you that you'll have to convert at some point.

Hi,

To tag onto this -- I ran into a similar issue.

Just for the sake of clarity -- I used 90 cents/ person/ mile and a distance of 10 miles. After converting it to dollars, I get $13.5/person/mile -- great.

Now, when I am plugging in my values in the answer choices, how do I know which value to plug for R. Am I supposed to plug in the cost(in cents) or am I supposed to plug the cost(in dollars). I plugged in the dollar cost and my answer was off, but if I plugged in the cost in cents, then the answer was correct. This seems a little counterintuitive since the answer was supposed to be in dollars.

How am I supposed to know as to which value to plug in the above equation?

[RonPurewal]

How am I supposed to know as to which value to plug in the above equation?

you just do exactly what the words say.

A certain NYC taxi driver has decided to start charging a rate of r cents per person per mile

...there you go.

[RonPurewal]

oh, and, this:

Just for the sake of clarity -- I used 90 cents/ person/ mile and a distance of 10 miles. After converting it to dollars, I get $13.5/person/mile -- great.

the red stuff has the wrong units.

once you've multiplied by 10 miles, it's just 13.5 $/person. it's not "per mile" anymore.

[RonPurewal]

and, yes, the final answer is dollars even though your input for "r" is in cents.

this sort of thing isn't a "trick"; it's totally standard. for instance, in real life, we consider lots of trips of 20-30 minutes at speeds of xxxxx miles per hour.

also, if you send messages above the limit on a cell phone, that's usually something like 20 cents per extra message ... but you'll definitely calculate your final "answer" in dollars.