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

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
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6
8

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

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!

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

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

Like this post

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

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Gurome, Inc.
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karthikpandian19: Legendary Member; Posts: 1665; Joined: Thu Nov 03, 2011 7:04 pmFollowed by: 70 members; Thanked: 165 times

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.

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

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

I posted a solution here:

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

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.

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

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

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

by ronnie1985 » Mon Dec 26, 2011 8:30 pm

Combined speed = 1/8+1/12 = 5/24 hr^-1
If x set of novices and chef required then x*5/24 = 5/8 = > x = 3

Follow your passion, Success as perceived by others shall follow you

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

by karthikpandian19 » Tue Dec 27, 2011 9:41 pm

OA is 6

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