OG DS-Q269

[Patty Wang]

Q-269 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 calcaulated by Martin on this 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.

請教一下，這題的語意不是很懂，而且不知如何去做題目？

謝謝！！

[HHC]

每當martin 的帳單介於10元和99元之間時，他就把帳單金額的十位數乘以二作為小費。若martin 最近的帳單金額介於10元和99元，martin 所算的小費是否大於帳單金額的15%？
1.帳單金額介於 $15 和 $50.
2.Martin 算出來的小費是 $8.

1.若帳單金額$15，小費就是$2，佔帳單金額13.3%；若帳單金額$50，小費為$10，佔帳單金額20% => 不確定是否大於帳單金額的15%
2.Martin 算出來的小費是 $8，表示帳單金額介於 $40 和 $49。若帳單金額為$40，小費就佔帳單金額20%；若帳單金額為$49，小費則佔帳單金額16.3%；即使帳單金額為$49.99，小費也佔帳單金額16% => 必定大於帳單金額的15%

選B