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标题: 300难题DS 求解在线等 [打印本页]

作者: 白露丹枫 时间: 2019-11-14 16:39
标题: 300难题DS 求解在线等

At a certain university recreation center, a member can receive a 30-minute massage,a 60-minute massage, or a 90-minute massage and is charged $0. 50 per minute for each massage. A member receiving a massage is charged the same fixed amount for each additional service, such as nutrition advice or a fitmess evaluation. At this center, what is the total charge to a member for a 60-minute massage and 3 additional services?

(1)At this recreation center, Jordan, a member, had a massage and 3 additional services for a total charge of $37.50.

(2)At this recreation center, Ryan, a member, had a massage and 2 additional services for a total charge of $60.00.

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

作者: Parker_1997 时间: 2019-11-14 17:21
Description

A massage may cost 15,30,45

An additional service fixed (f stands for the price per service)

Statement 1

random(15,30,45) +3f = 37.5

Indication for condition 1: Jordan did not choose a $ 45 massage since f is positive

Statement 2

random(15,30,45) +2f = 60

Indication for condition 2 : Ryan must choose a higher price massage than Jordan did

because Ryan had few additional services but a higher total charge.

Ask: 30 + 3f = ? Actually we need to find out whether f is solved out uniquely

My idea:

First, we can easily know that only one statement can not lead to unique result of f, since each has more than one choice for time of massage.

Next, combine condition 1 &2 , we still have 3 cases according to indications before:

1. Jordan's massage: 15 ;  Ryan's: 30    15+3f = 37.5 30+ 2f = 60 f1=7.5  f2=15    f is not fixed
2. Jordan's massage: 15 ;  Ryan's: 45    f1 = 7.5 f2 = 7.5    bravo
3. Jordan's massage: 30 ;  Ryan's: 45    f1=2.5  f2=7.5    f is not fixed

Therefore, we can reduce down to only one case by combining statement 1 & 2 , in other words, we have unique result to answer 30+3f.

作者: yybabya 时间: 2019-11-14 17:25
条件一推不出来，因为有可能是15块的A套餐，也可能是30块的B套餐。条件二同理。条件一＋条件二可以，因为套餐只有三种。用Jordan的信息分情况讨论，假设他是A套餐，算出一个additional service应该多少钱，带入第二个条件算，看算出来的massage是不是特定的那三种分钟。假设Jordan是B套餐，同理这么算。

作者: 白露丹枫 时间: 2019-11-14 17:42
标题: merci parker，u inspire all of us

Parker_1997 发表于 2019-11-14 17:21
Description

A massage may cost 15,30,45

同意！

作者: 白露丹枫 时间: 2019-11-14 17:45

yybabya 发表于 2019-11-14 17:25
条件一推不出来，因为有可能是15块的A套餐，也可能是30块的B套餐。条件二同理。条件一＋条件二可以，因为套 ...

真的，到了分类真有点不适应，容易的题已经让我有一种不用分类的假象，thanks bro

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