Hi annaleroy,
There are a couple of different ways to approach this question. Regardless of what method you choose, you will have to stay organized, take plenty of notes and do enough work to prove your answer. There's a great opportunity in this question to TEST VALUES and do a little arithmetic.
Here, we know that there are 3 items purchased. We know that the MOST EXPENSIVE ITEM got a 20% discount and the other 2 items got a 10% discount. We're asked for the TOTAL amount of the discounts.
Fact 1: The AVERAGE of the prices of the 3 items was $30.
If the 3 items cost: $40, $30 and $20, then the TOTAL discount = $8 + $3 + $2 = $13
If the 3 items cost: $50, $30 and $10, then the TOTAL discount = $10 + $3 + $1 = $14
Fact 1 is INSUFFICIENT
Fact 2: The most expensive item was $50
This tells us that the discount for that 1 item was (.2)($50) = $10, but we don't know the cost of the other 2 items, so we don't know what the discounts will be.
Fact 2 is INSUFFICIENT
Combining Facts though, we know…
1) The average of the 3 items is $30, so the SUM of the 3 items = $90
2) The most expensive item is $50, so the OTHER 2 items sum up to $40
So, we know that that $50 item gets the 20% discount and the other two items (that add up to $40) each get 10%. The discount will be $50(20%) + $40(10%) = $10 + $4 = $14.
Combined, SUFFICIENT
Final Answer:
GMAT assassins aren't born, they're made,
Rich
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