Data Sufficiency

whenever martin has a resturant bill with an amount between $10 and $99, he calcuates the dollar amount of the tip as 2 times the tens digit of the amount of his bill. If the amount of martine's most recewnt restaurant bill was between $10 and $99, was the tip calculated by marin on the bill greater than 15 precent of the amout of the bill?

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

2) the tip calcuated by marin was $8


[spoiler]I just dont seem to understand the statiment 2) itself....could anyon kindly explain?? [/spoiler]

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

lets say the bill amount is 21 so the tip is 2 times the tens digit = 1*2 = 2
which is approx 10% of the bill

lets say the bill amount is 24 so the tip is 2 times the tens digit = 4*2 = 8
which is approx 33% of the bill
INSUFF

2. the tip calcuated by martin was $8

lets say the bill amount is 24 so the tip is 2 times the tens digit = 4*2 = 8
which is approx 33% of the bill

lets say the bill amount is 94 so the tip is 2 times the tens digit = 4*2 = 8
which is approx 9% of the bill
INSUFF

Both together

Bill amounts can be 24, 34 and 44 and tip is $8 everytime.
The tip is 33, 23 and 18 percent respectively of the amount of bill.

Ans C.

sorry, answer is not correct - can anyone help?

he calcuates the dollar amount of the tip as 2 times the tens digit of the amount of his bill

stmt 1:

the amount of the bill was between $15 and $50

so tip can be between $2 & $10

& 15% OF 15 = 2.25 & 50 is 7.5

INSUFF

stmt 2:

tip was $8

so tens digit of the bill would be 4

so the amt can be between $40 and $49

15 % of 40 = 6 <8> 15% of $49 thus < $8

so tip was greater than 15%

B

1) the amount of the bill was between $15 and $50
this statement is insufficient because in this range, you can have a tip that is below 15% and a tip that is above 15%. For example, if the bill was $10, then a $2 tip is a 20% tip. If the bill was $19, then the tip is 10.5%.

2) the tip calcuated by marin was $8

This statement is sufficient. An $8 tip means this bill was between $40 and $49 dollars. For this range, the tip will always be over 15%. For example, a $40 bill and an $8 tip is a 20% tip. A $49 bill, and $8 tip is a 16% tip.

Thus the answer it B.