Eggs in Loach s Grocery can only be bought individually

'B' it is.

1) insufficient
2) sufficient
30 individually = $ 4.80
9 cartons of 12 eggss each $1 = $9
2 cartons of 6 eggs each $0.60 = $1.20 TOTAL $15.00 - 11 Cartons.

Notice that the average price paid is exactly the price of a carton of 6. How can this happen? (clue)

These are the deadly ones

how does one go about it and conclude unique soln for state 1 -

Shampoo,

can you please shed some light on this ?

I know B gives the answer but not sure about A.

Somehow I feel A will give the answer like 30 individual, 3 cartons of 6 and 9 cartons of 12.

So I go for D.

Very true.

B does give the answer. But trying to find out A will be very long.

Gut feeling in these cases is that the answer should be D

Exactly my feelings too! Somehow after solving numerous problems of various difficulty I am starting to get a sixth sense on these traps. I hope that my gut feeling would not let me down on the exam date...

So, anybody knows how to show that (A) is sufficient too?

can we have the official answer, i'd go with D, i dont see how any other way A will yield 150.

A mathematical approach to solve this would be:

x = No of dozens
y = No of half-dozens
z = No of individual eggs

From the stem,
x + 0.6y+0.16z = 15 --(A)

From 2:
x = 9
z = 30

We can find y (as everyone here has found) and only one such y exists. And hence SUFF.

Condition #1.
Given
x + 0.6y+0.16z = 15 --(A)
12x+6y+z = 150 --(B)

(From #2) x = 9, y = 2 and z = 30 is defenitely one of the solutions. We are looking for alternate solution

(A)*10 - (B) gives
10x = 3z

We ALREADY KNOW that
x = 9, z = 30 --> y = 2 is a valid solution
Try to find other integer solutions for ths:
x = 3, z = 10 --> y = 104/6 Not an integer. Invalid solution
x = 6, z = 20 --> y = 58/6 Not an integer. Invalid solution
x = 12, z = 40 --> y becomes -ve. No neeto to check further

#1. is also sufficient. Hence D.

But as everyone here mentioned, all of this analysis takes a hell lot of time. It is not worth spending more than 3 minutes.

It pays to be observant. From (1), the average price of the eggs was $0.10, which means that the average price of the eggs bought individually or by the dozen was also $0.10

As an equation,
(0.16x+ y)/(x+12y)=0.1 x=no. of ind. eggs, y=no. of dozens

so 3x=10y (x,y) could be (0,0),(10,3),(20,6) or (30,9)

But no. of eggs sold in 6 packs must be multiple of 6

Thus 150-x-12y must be a multiple of 6

Thus x must be 0 or a multiple of 6
Thus x must be either 0 or 30, but x cannot be 0 since x+y must be greater than 0
Thus x=30, y=9 and no. of 6 packs must be 2

Therefore (1) is sufficient, as is (2) OA: D
A friend of mine did the GMAT last week and this was similar to the last question