GmatPrep?? (Revolutions)

IMO E

60 seconds (1 min) = x revolutions
k seconds = (kx)/60 revolutions

wots the OA

Correct..but how did you arrive to your answer.

dferm wrote:Correct..but how did you arrive to your answer.

x revolutions per minute

x/60 revolutions per seconds

kx/60 revolutions per k seconds

Hence E.

CAN YOU PLUG IN #'S..

well yeah you can plug in numbers

for instance the wheel completes 10(X) rev in 1 min or 60 secs

how many rev does it complete in 15 (K) secs

60 secs = 10 rev
15 secs = z rev

cross multiply and solve for z = (15*10)/60
which is the same as (kx)/60

btw i just cross multiplied the values to get the answer

dferm wrote:CAN YOU PLUG IN #'S..

Sure why not!

let x be 60

60 revolutions in 1 minute.

60 revolutions in 60 secs.

1 revolution per sec.

let k be 10

10*1= 10

if you plugin values of x and k in the answer choices only E will give 10 as the answer.

Here's how I solved...

pick numbers for both x and k. The easiest would be 10 for x and 120 for k since there are 60 seconds in a minute so the question would really be asking you how many revolutions are made in two minutes. In this case it would be 20 so all we need to do is plug in the values for x =10 and k = 120 into each of the answer choices (i would start with C) and see which ones yields a value of 20.

E gives us a value of 20.

Hope this helps!!