Data Sufficiency

alanforde800Maximus wrote:A certain store sells only records and CD's. All CD's cost $7.82, including tax, and all records cost $4.18, including tax. Yesterday, did John buy more than 5 records at this store?

a) Yesterday, John spent less than $25 at the store.
b) Yesterday, John bought at least one CD at the store.

Target question: Did John buy more than 5 records ?

Given: CD's cost $7.82, and records cost $4.18

Statement 1: Yesterday, John spent less than $25 at the store.
Notice that it costs $25.08 to buy 6 records, since (6)($4.18) = $25.08
So, if John spent less than $25, it is impossible for him to buy 6 or more records.
In other words, John did NOT buy more than 5 records
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: Yesterday, John bought at least one CD at the store
Since there's no information restricting the number of purchases John made, we can see that statement 2 is NOT SUFFICIENT.
For example, here are two possible cases:
Case a: John bought 1 CD and 0 records. So, John did NOT buy more than 5 records
Case b: John bought 1 CD and 10 records. So, John DID buy more than 5 records
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Answer = A

Cheers,
Brent