DS

[kop]

Alice has $15, which is enough to buy 11 muffins and 7 brownies, is $45 enough to buy 27 muffins and 27 brownies?
(1) $15 is enough to buy 7 muffins and 11 brownies.
(2) $15 is enough to buy 10 muffins and 8 brownies.


What is the answer for this?
I got D

[theCodeToGMAT]

15>= 11M + 7B -(1)

To find: 45>= 27M + 27B

Statement 1:
15>= 7M + 11B -(2)
Adding (1) & (2)
30>= 18M + 18B
30/18 >= M + B
Multiply both sides by 27
30*27/18 >=27M + 27B
45 >= 27M + 27B
SUFFICIENT

Statement 2:
15>= 10M + 8B -(3)
Let B=0
3/2 >= M
So, 27*3/2 >= 27M
Let M=0
15/8 >= B
So, 27*15/8 >= 27B
We cannot confirm whether 45 is enough
INSUFFICIENT

According to me, answer is [spoiler]{A}[/spoiler]

[Uva@90]

Alice has $15, which is enough to buy 11 muffins and 7 brownies, is $45 enough to buy 27 muffins and 27 brownies?
(1) $15 is enough to buy 7 muffins and 11 brownies.
(2) $15 is enough to buy 10 muffins and 8 brownies.


What is the answer for this?
I got D

Kop,
An another Approach,
Let M = Muffins and B = Brownies
Given: 11M +7B = 15(11M and 7B can be purchased using 15$)
To Find: 27M + 27B = 45
Divide above equation by 3
9M + 9B = 15
which mean is 15$ enough to buy 9M and 9B or not ?
or can be said as "is 2M can be replaced by 2B"(as 11M+7B =15)

Statement1 : $15 is enough to buy 7 muffins and 11 brownies

7M +11B =15$
Since, 4M can be replaced by 4B. Hence 2M can be replaced by 2B

Sufficient.

Statement 2: $15 is enough to buy 10 muffins and 8 brownies.

10M+8B = 15$
from this we can get to know that 1M can be replaced by 1B.
So we can't say surely that 2M can be replaced by 2B .
Hence In-sufficient.

Answer is A

Hope it helps you.

Regards,
Uva.

[bristle]

I still cant figure this question out

2M can be replaced by 2B =Sufficient
1M can be replaced by 1B =insufficient

The question seems to not have asked for either but for sufficiency. I don't know what am missing

9M+ 9B = 15
7M+11B = 15 2M-2B
10M+8B = 15 -M+B

I still see both being independently able to provide a yes/no answer
Can some one further explain

[Gmatbuddy]

You can simplify the question, making it easier to calculate or pick numbers.