DS-GMAT PREP

Question

Please help me to solve this problem.

jax91 · Answer

let wage1 = x
so wage2= x+5

increase them by 6% each.
 w1 = x + (6/100)x
w2= (x+5)(1+6/100) = x + (6/100)x + 5 + 5(6/100)

difference = w2 - w1 =   - x + (6/100)x 
=> 5 + 5(6/100) (which is in $)

so solvable by 1.

ngoctraiden1905 · Answer

1/ before J=5+M (1)
After J'=1.06 J, M'=1.06 M
multiply each side of equation(1) by 1.06 we have
J' = M' + 5*1.06 sufficient
2/ not sufficient
So ans is A

Bunuel · Answer

First note that we are asked to determine the difference between the increased wages, not the wages themselves.

(1) Difference between the wages before increase was 5$, increase was 6%. Here comes the tricky thing: NO LONG CALCULATIONS ARE NEEDED with variables and other things. The new difference would be 5$*(1+6%)=5*1.06=5.3$ (The difference between the wages increased by the SAME percent, as the wages themselves) Sufficient

Also note that we wouldn't be able to determine new difference if the increases were not the same.

(2) We know the ratio between the wages. Not sufficient.

A.

Syed · Answer

Hi Bunuel, thanks a lot for staying on the discussion loop. I am learning a lot from your discussion. Could you please elaborate "HOW U CAME TO CONCLUDE THAT WE WON'T BE ABLE TO CALCULATE THE ABSOLUTE $ AMOUNT, IF THE % INCREASE WERE DIFFERENT.

Plz note that I have recalculated the increase with different % increase for the two employees. INDEED, I found the $ amount varies. My Q is "how you come to the conclusion quickly? What is the thought process?"

Please help me to improve.
--------------------------
+1 for you Bro...

Bunuel · Answer

Let's say that A's wage is 100$ and B's - 150. Difference 50$.

In the case when their wages increase (or decreases), by the same percent 100 increases as fast as 150, so the difference increase by the same percent. For 10% --> 100*1.1=110 , 150*1.1=165 --> difference 55, the same increase (10%).

BUT in the case when their wages increase (or decrease), by different percent, 100(base) increases slower (or faster depending which one has bigger increase) than 150(base), but we can not determine difference, not know their absolute values and knowing only rates. For example:
A=100, A's increase  10% 
B=150, B's increase  20% 
A after increase=110$, B after increase=180$ --> difference 70 (40% increase in difference)

BUT if:

A=100, A's increase  10% 
B=200, B's increase  20% 
A after increase=110$, B after increase=240$ --> difference 130 (160% increase in difference)
As we try bigger and bigger values for B increase in difference will be bigger and bigger.

So, it's not possible to determine the percent increase knowing only the difference and the increase rates, when rates are not the same.

Hope it's clear.

Syed · Answer

Bunuel,

Thanks a huge lot again...

gurpreet07 · Answer

Can someone please help me solve this....

chetan2u · Answer

ans shud be a...
 ans edited

gurpreet07 · Answer

nopes the OA is not C
you can give it a try again

chetan2u · Answer

hi .. how could i miss such a thing..
 ans A....
 existing diff is already given as $5..... therefore the diff after raise can be found by adding 6% of $5 to $5=$5.30

DS-GMAT PREP

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards