gmatbusters wrote:
Project DS Butler: Day 22: Data Sufficiency (DS44)
For DS butler Questions Click HereExactly how many bonds does Bob have?
(1) Of Bob’s bonds, exactly 21 are worth at least $5,000 each
(2) Of Bob’s bonds, exactly 65 percent are worth less than $5,000 each
Target question: Exactly how many bonds does Bob have? Statement 1: Of Bob’s bonds, exactly 21 are worth AT LEAST $5,000 each We have no idea how many of Bob's bonds are worth LESS THAN $5000 each
Statement 1 is NOT SUFFICIENT
Statement 2: Of Bob’s bonds, exactly 65 percent are worth LESS THAN $5,000 eachThere are infinitely many scenarios that satisfy statement 2. Here are two:
Case a: Bob as a total of 100 bonds, 65 of which are worth less than $5,000 each, and 35 of which are worth at least $5,000 each. In this case, the answer to the target question is
Bob has 100 bondsCase b: Bob as a total of 200 bonds, 130 of which are worth less than $5,000 each, and 70 of which are worth at least $5,000 each. In this case, the answer to the target question is
Bob has 200 bondsSince we cannot answer the
target question with certainty, statement 2 is NOT SUFFICIENT
Statements 1 and 2 combined Statement 2 tells us that 65% of the bonds are worth
less than $5,000 each, which also means 35% of the bonds are worth
at least $5,000 each
Statement 1 tells us that 21 bonds are worth
at least $5,000 each
Let T = the total number of bonds that Bob owns
So, we can write: 35% of T = 21
In other words, 0.35T = 21
Since we COULD solve this equation for T, we COULD answer the
target question with certainty
As such, the combined statements are SUFFICIENT
Answer: C
Cheers,
Brent
_________________
Brent Hanneson – Creator of gmatprepnow.com
I’ve spent the last 20 years helping students overcome their difficulties with GMAT math, and the biggest thing I’ve learned is…
Many students fail to maximize their quant scores NOT because they lack the skills to solve certain questions but because they don’t understand what the GMAT is truly testing -
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