Rate problem

BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

This topic has expert replies

Post new topic Post Reply

Previous Topic Next Topic

karthikpandian19: Legendary Member; Posts: 1665; Joined: Thu Nov 03, 2011 7:04 pm; Thanked: 165 times; Followed by:70 members

Rate problem

by karthikpandian19 » Mon Dec 26, 2011 1:13 am

On a wedding catering service, An experienced chef can prepare a service for a wedding in 8 hours while an novice chef would finish the preparations in 12 hours.

If the catering service employs the same number of novice and experienced chefs, then how many chefs would it take to prepare a wedding service in 1 hour and 36 minutes?

2
3
4
6
8

Quote

Source: Beat The GMAT — Problem Solving | Mon Dec 26, 2011 1:13 am

pemdas: Legendary Member; Posts: 1084; Joined: Fri Apr 15, 2011 2:33 pm; Thanked: 158 times; Followed by:21 members

by pemdas » Mon Dec 26, 2011 1:57 am

firstly convert 36 mins to hours

1/2 + 1/10=6/10=3/5 hours is the same as 36 mints

speed chef --> 1/8
speed novice --> 1/12

since both are combined in equal numbers, just tale combined speed (rather easy than if it were diff. coeff.) 1/8+1/12=5/24
x is the number of chefs or noives and find the reciprocal of (1+3/5) or 1h.36 mints since speed=1//time
(5/24)*x=5/8, 5x/24=5/8, 5x=24*5/8, x=24/8=3

we need 3 chefs (the same number of novices are req.)

b

karthikpandian19 wrote:On a wedding catering service, An experienced chef can prepare a service for a wedding in 8 hours while an novice chef would finish the preparations in 12 hours.

If the catering service employs the same number of novice and experienced chefs, then how many chefs would it take to prepare a wedding service in 1 hour and 36 minutes?

2
3
4
6
8

Success doesn't come overnight!

Quote

karthikpandian19: Legendary Member; Posts: 1665; Joined: Thu Nov 03, 2011 7:04 pm; Thanked: 165 times; Followed by:70 members

by karthikpandian19 » Mon Dec 26, 2011 4:25 am

@pemdas.....

It should be 6 Chefs (3 Chefs + 3 Novice)

24/5 hrs with 2 chefs (1 chef + 1 novice), so 8/5 hrs with ??? Chefs

= (24/5)/(8/5) * 2

= 6

pemdas wrote:firstly convert 36 mins to hours 1/2 + 1/10=6/10=3/5 hours is the same as 36 mints

speed chef --> 1/8
speed novice --> 1/12

since both are combined in equal numbers, just tale combined speed (rather easy than if it were diff. coeff.) 1/8+1/12=5/24
x is the number of chefs or noives and find the reciprocal of (1+3/5) or 1h.36 mints since speed=1//time
(5/24)*x=5/8, 5x/24=5/8, 5x=24*5/8, x=24/8=3

we need 3 chefs (the same number of novices are req.)

b
karthikpandian19 wrote:On a wedding catering service, An experienced chef can prepare a service for a wedding in 8 hours while an novice chef would finish the preparations in 12 hours.

If the catering service employs the same number of novice and experienced chefs, then how many chefs would it take to prepare a wedding service in 1 hour and 36 minutes?

2
3
4
6
8

Quote

GMAT/MBA Expert

Anurag@Gurome: GMAT Instructor; Posts: 3835; Joined: Fri Apr 02, 2010 10:00 pm; Location: Milpitas, CA; Thanked: 1854 times; Followed by:523 members; GMAT Score:770

by Anurag@Gurome » Mon Dec 26, 2011 5:29 am

karthikpandian19 wrote:On a wedding catering service, An experienced chef can prepare a service for a wedding in 8 hours while an novice chef would finish the preparations in 12 hours.

If the catering service employs the same number of novice and experienced chefs, then how many chefs would it take to prepare a wedding service in 1 hour and 36 minutes?

2
3
4
6
8

Time taken by experienced chef = 8 hours
Time taken by novice chef = 12 hours

Let us assume that the catering service employs X novice and experienced chefs.
1 hr 36 mins = 1 36/60 = 1 3/5 = 8/5
Then, 1/(8/5)= X(1/8 + 1/12)
5/8 = X(5/24)
1 = X/3
X = 3
Therefore, total number of chefs required = 3 + 3 = 6

The correct answer is D.

Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/

Quote

karthikpandian19: Legendary Member; Posts: 1665; Joined: Thu Nov 03, 2011 7:04 pm; Thanked: 165 times; Followed by:70 members

by karthikpandian19 » Mon Dec 26, 2011 5:41 am

I knew this is simple, but i messed up with the Rate / work / time

Can you explain with formula approach for Rate/work/time

Anurag@Gurome wrote:
karthikpandian19 wrote:On a wedding catering service, An experienced chef can prepare a service for a wedding in 8 hours while an novice chef would finish the preparations in 12 hours.

If the catering service employs the same number of novice and experienced chefs, then how many chefs would it take to prepare a wedding service in 1 hour and 36 minutes?

2
3
4
6
8
Time taken by experienced chef = 8 hours
Time taken by novice chef = 12 hours

Let us assume that the catering service employs X novice and experienced chefs.
1 hr 36 mins = 1 36/60 = 1 3/5 = 8/5
Then, 1/(8/5)= X(1/8 + 1/12)
5/8 = X(5/24)
1 = X/3
X = 3
Therefore, total number of chefs required = 3 + 3 = 6

The correct answer is D.

Quote

GMATGuruNY: GMAT Instructor; Posts: 15539; Joined: Tue May 25, 2010 12:04 pm; Location: New York, NY; Thanked: 13060 times; Followed by:1906 members; GMAT Score:790

by GMATGuruNY » Mon Dec 26, 2011 5:53 am

I posted a solution here:

https://www.beatthegmat.com/ps-caterers-t89876.html

Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3

Quote

user123321: Master | Next Rank: 500 Posts; Posts: 385; Joined: Fri Sep 23, 2011 9:02 pm; Thanked: 62 times; Followed by:6 members

by user123321 » Mon Dec 26, 2011 6:01 am

pemdas wrote:firstly convert 36 mins to hours 1/2 + 1/10=6/10=3/5 hours is the same as 36 mints

speed chef --> 1/8
speed novice --> 1/12

since both are combined in equal numbers, just tale combined speed (rather easy than if it were diff. coeff.) 1/8+1/12=5/24
x is the number of chefs or noives and find the reciprocal of (1+3/5) or 1h.36 mints since speed=1//time
(5/24)*x=5/8, 5x/24=5/8, 5x=24*5/8, x=24/8=3

we need 3 chefs (the same number of novices are req.)

b
karthikpandian19 wrote:On a wedding catering service, An experienced chef can prepare a service for a wedding in 8 hours while an novice chef would finish the preparations in 12 hours.

If the catering service employs the same number of novice and experienced chefs, then how many chefs would it take to prepare a wedding service in 1 hour and 36 minutes?

2
3
4
6
8

I think 6. 3 novice & 3 experienced.

user123321

Just started my preparation

Want to do it right the first time.

Quote

Abhishek009: Master | Next Rank: 500 Posts; Posts: 359; Joined: Wed Mar 11, 2009 4:37 am; Location: Kolkata, India; Thanked: 50 times; Followed by:2 members

by Abhishek009 » Mon Dec 26, 2011 7:25 am

karthikpandian19 wrote:On a wedding catering service, An experienced chef can prepare a service for a wedding in 8 hours while an novice chef would finish the preparations in 12 hours.

If the catering service employs the same number of novice and experienced chefs, then how many chefs would it take to prepare a wedding service in 1 hour and 36 minutes?

2
3
4
6
8

Let the total work be 96 units....

Now , efficiency of the chief is 12 units/hr

Efficiency of the inexperienced chief is 8units/hr

Say " a " no of experienced and in experienced chiefs r recruited..

So , the work done by them in 1 hour is 20a units...

Hence , they prepare 20 units in 60 minutes...

Now the time given is 96 minutes...

In 60 mints 20 units is produced

In 1 mint 1/3 units is produced

Hence in 96 mints ( 1/3 )96 => 32 units is produced...

Now , we have considered the entire Cake as 96 units , so the total no of people required is 96 / 32 => 3

hence we require 3 3 novice & 3 experienced chiefs...

Abhishek

Quote

ronnie1985: Legendary Member; Posts: 626; Joined: Fri Dec 23, 2011 2:50 am; Location: Ahmedabad; Thanked: 31 times; Followed by:10 members