Data Sufficiency

Hi jjjinapinch,

We're told that all donuts are priced equally and all bagels are priced equally (meaning that all donuts cost the same price and all bagels cost the same price). We're asked for the total price of 5 donuts and 3 bagels. In simple terms, we're asked for the value of 5D + 3B....

1) At the bakery, the total price of 10 donuts and 6 bagels is $12.90.

With the information in Fact 1, we can create the following equation:
10D + 6B = $12.90

We can simplify this equation by dividing both sides by 2, which gives us...
5D + 3B = $6.45
We now have the exact answer to the question: $6.45
Fact 1 is SUFFICIENT

2) At the bakery, the price of a donut is $0.15 less than the price of a bagel.

With the information in Fact 2, we can create the following equation:
D = B - $0.15
Unfortunately, the answer to the question will vary depending on the values of B and D...
For example, the values....
B = $1.00, D = $0.85
B = $2.00, D = $1.85
...would lead to different answers to the given question
Fact 2 is INSUFFICIENT

Final Answer: A

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

jjjinapinch wrote:At a bakery, all donuts are priced equally and all bagels are priced equally. What is the total price of 5 donuts and 3 bagels at the bakery?

(1) At the bakery, the total price of 10 donuts and 6 bagels is $12.90.
(2) At the bakery, the price of a donut is $0.15 less than the price of a bagel.

We are given that all donuts are priced equally and all bagels are priced equally and need to determine the total price of 5 donuts and 3 bagels. Let's start by defining some variables.

D = the price per donut

B = the price per bagel

Thus we need to determine: 5D + 3B = ?

Statement One Alone:

At the bakery, the total price of 10 donuts and 6 bagels is $12.90.

Using the information in statement one, we can create the following equation:

10D + 6B = 12.90

We can simplify the equation by dividing the entire equation by 2.

5D + 3B = 6.45

Thus, the price for 5 donuts and 3 bagels is $6.45. Statement one alone is sufficient to answer the question. We can eliminate answer choices B, C, and E.

Statement Two Alone:

At the bakery, the price of a donut is $0.15 less than the price of a bagel.

We can express D in terms of B:

D = B - 0.15

Substituting B - 0.15 for D, we get:

5(B - 0.15) + 3B

5B - 0.75 + 3B

8B - 0.75

However, without knowing anything about the price of either D or B, or the total amount spent, we cannot determine the sum of 5D + 3B. Thus, statement two is insufficient.

Answer: A