singhmaharaj wrote:Whenever Martin has a restaurant bill with an amount between $10 and $99, he calculates the dollar amount of the tip as 2 times the tens digit of the amount of his bill. If the amount of Martin's most recent restaurant bill was between $10 and $99, was the tip calculated by Martin on the bill greater than 15 percent of the amount of the bill?

1) The amount of the bill was between $15 and $50.

2) The tip calculated by Martin was $8.

Target question: Was the Martin's tip greater than 15 percent of the amount of the bill?

Given: Martin's most recent restaurant bill was between $10 and $99

Statement 1: The amount of the bill was between $15 and $50.
Let's TEST some possible values of the bill.
Case a: the bill was $16, which means Martin paid a $2 tip. In this case, Martin's tip is LESS THAN 15% of the bill
Case b: the bill was $40, which means Martin paid an $8 tip. In this case, Martin's tip is GREATER THAN 15% of the bill
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: The tip calculated by Martin was $8.
Let's test some EXTREME POSSIBLE VALUES of the bill.
Case a: the bill was $40, which means Martin paid a $4 tip. In this case, Martin's tip is GREATER THAN 15% of the bill
Case b: the bill was $49.99, which means Martin paid an $8 tip. In this case, Martin's tip is GREATER THAN 15% of the bill
Since both of the EXTREME VALUES yield the same response to the target question, we can be certain that statement 2 is SUFFICIENT

Answer = B

Cheers,
Brent