GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 21 Oct 2019, 09:26

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Richard works as a waiter in an elegant downtown restaurant. His avera

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 58409
Richard works as a waiter in an elegant downtown restaurant. His avera  [#permalink]

### Show Tags

01 Apr 2018, 10:28
00:00

Difficulty:

15% (low)

Question Stats:

91% (01:33) correct 9% (01:05) wrong based on 33 sessions

### HideShow timer Statistics

Richard works as a waiter in an elegant downtown restaurant. His average (arithmetic mean) gratuity per day over the past 10 workdays is $200. If Richard’s average gratuity per day for the first six of the past 10 workdays was$180, what was his average gratuity per day for the last four of the past 10 workdays?

(A) $210 (B)$220
(C) $225 (D)$230
(E) $240 _________________ Manager Joined: 05 Feb 2016 Posts: 168 Location: India Concentration: General Management, Marketing WE: Information Technology (Computer Software) Re: Richard works as a waiter in an elegant downtown restaurant. His avera [#permalink] ### Show Tags 01 Apr 2018, 11:02 Bunuel wrote: Richard works as a waiter in an elegant downtown restaurant. His average (arithmetic mean) gratuity per day over the past 10 workdays is$200. If Richard’s average gratuity per day for the first six of the past 10 workdays was $180, what was his average gratuity per day for the last four of the past 10 workdays? (A)$210
(B) $220 (C)$225
(D) $230 (E)$240

average gratuity for 10days=(x+y)/10=200

average gratuity for 6days=x/6=180

Putting in equation 6*180+y=2000,y= 920

average gratuity for 4days=y/4=z=920/4=230

option D
Senior SC Moderator
Joined: 22 May 2016
Posts: 3565
Richard works as a waiter in an elegant downtown restaurant. His avera  [#permalink]

### Show Tags

01 Apr 2018, 13:45
Bunuel wrote:
Richard works as a waiter in an elegant downtown restaurant. His average (arithmetic mean) gratuity per day over the past 10 workdays is $200. If Richard’s average gratuity per day for the first six of the past 10 workdays was$180, what was his average gratuity per day for the last four of the past 10 workdays?

(A) $210 (B)$220
(C) $225 (D)$230
(E) $240 Weight the averages. Let 4 days' average = $$x$$ 6-day average =$180
Total 10-day average = $200 $$4(x) + 6(180) = 10(200)$$ $$4x + 1,080 = 2,000$$ $$4x = 920$$ $$x = 230$$ Answer D Similar method - a little less direct $$A * n = S$$ (10-day Sum) - (6-day Sum) = (4-day Sum) Divide result by 4 for last four days' average, because (n=4): $$A= \frac{S}{n}$$ Sum for all 10 days: ($200 * 10) = $2,000 Sum for 6 days: ($180 * 6) = $1,080 Sum for 4 days: ($2,000 - $1,080) =$920
Average for 4 days: $$\frac{920}{4} = 230$$ per day

_________________
SC Butler has resumed! Get two SC questions to practice, whose links you can find by date, here.

Instructions for living a life. Pay attention. Be astonished. Tell about it. -- Mary Oliver
Manager
Joined: 23 Sep 2016
Posts: 233
Re: Richard works as a waiter in an elegant downtown restaurant. His avera  [#permalink]

### Show Tags

02 Apr 2018, 22:20
Bunuel wrote:
Richard works as a waiter in an elegant downtown restaurant. His average (arithmetic mean) gratuity per day over the past 10 workdays is $200. If Richard’s average gratuity per day for the first six of the past 10 workdays was$180, what was his average gratuity per day for the last four of the past 10 workdays?

(A) $210 (B)$220
(C) $225 (D)$230
(E) \$240

IMO D avg of 10days= 200 total= 200*10=2000
perday for 1st 6 days =180
total of 6 days= 180*6=1080
now total of last 4 days= 2000-1080=920
now perday grtuity= 920/4= 230
Re: Richard works as a waiter in an elegant downtown restaurant. His avera   [#permalink] 02 Apr 2018, 22:20
Display posts from previous: Sort by

# Richard works as a waiter in an elegant downtown restaurant. His avera

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne