A store sells two types of birdfeeder: Alphas and Bravos.

OA seems to be A. I too think it is C. Can someone confirm?

Thanks....should've seen that

Bunuel, you really are unbreakable!
Kudos for the question anyone?

Nice question. Kudos to you for posting it.

This question exemplifies why its really important to multiply out the question stem and answers and figure out exactly what it is asking for.

We know that the total number of birds that can be fed at one time is 50 and that B can feed two at a time and A can feed one.
Thus we know A+2B=50 (with A being the number of A birdfeeders sold and B being the umber of B birdfeeders sold)

(1) tells us that the price of the A was $15 and the price of B was $30
when we initially look at this, most people would assume that you cannot know the answer just from this, because we don't know how many total birdfeeders were sold, but let's put it into an equation
15A+30B--------> 15(A+2B)
because we know what A+2B equals (50), we can actually figure out the revenue from the two birdfeeders
15(50), not need to multiply it out we now know 1 works by itself.

(2) 40 Alphas were sold last month tells us that 5 betas were sold (A+2B=50)
however, since we don't know the price, we have no idea what the revenue is

Thus, our answer is A

Hi All,

Like most GMAT questions, DS questions are often based on patterns (even if you don't realize that a pattern is there). Some Test Takers are great at "pattern-matching", but even if you're not, you can usually find a hidden pattern (if one exists) by doing a little bit of work.

Here, we're told that there are 2 types of bird-feeders:
1) Alphas feed 1 bird at a time
2) Betas feed 2 birds at a time

We're also told that a number of feeders were sold and these feeders could feed 50 birds at once. Thus, we have our first equation:

A + 2B = 50

**Note: It's INTERESTING that Betas feed DOUBLE the number of birds - whoever wrote this question chose that multiple ON PURPOSE**

We're asked for the total REVENUE generated from the sale of those feeders.

Fact 1: The price of each Alpha is $15, the price of each Beta is $30.

This might not seem like enough information, but notice how the price of each Beta is DOUBLE the price of each Alpha....whoever wrote this question has now given us 2 pieces of data that are based on "doubles"....maybe there's a pattern here...

Let's run some TESTs:

IF...
A = 50
B = 0
50($15) + 0($30) = $750 revenue

IF....
A = 30
B = 10
30($15) + 10($30) = $750 revenue

IF....
A = 10
B = 20
10($15) + 20($30) = $750 revenue

It looks like the revenue is ALWAYS $750.
This IS enough information to answer the question.
Fact 1 is SUFFICIENT

Fact 2:40 Alphas were sold last month.

This tells us nothing about prices/revenue.
Fact 2 is INSUFFICIENT

Final Answer:

GMAT assassins aren't born, they're made,
Rich

Official Explanation:
From the words in the question stem, Extract the Equation. The problem indicates that Alphas can feed one bird at a time and
Bravos two. The problem also indicates that last month 50 birds could be fed at a time, so you have this:
Total number of birds fed = \(A + 2B = 50\), where A and B represent the number of birdfeeders of each type that have been sold.
To calculate the revenue, it seems you will need the prices of the birdfeeders and the number of birdfeeders, A and B.

(1) SUFFICIENT: Again Extract the Equation from the wording of the question:
Total revenue = \($15A + $30B = $15(A + 2B)\)
It turns out that you don't need to know A and B individually, since the question stem equation indicated that \(A + 2B = 50\).
Therefore total revenue equals \($15(A + 2B) = $15(50) = $750\).
It's true that there are many possible values of A and B that satisfy the condition that \(A + 2B = 50\). However, mathematically
every possible combination that satisfies this equation would lead to the same revenue of $750. The number of each type of
birdfeeder sold is irrelevant. In this sense, Extract the Equation can be similar to the Compute to Completion strategy,
because once the equation has been extracted, you may find that the multiple possibilities for the variables might converge to a
single answer to the specific question that's been asked.

(2) INSUFFICIENT: If there were 40 Alphas sold, there were 5 Bravos sold. But you still don't know the prices, so you can't
compute revenue.
The correct answer is (A)

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