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# A bakery opened yesterday with its daily supply of 40 dozen

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Math Expert
Joined: 02 Sep 2009
Posts: 61385
A bakery opened yesterday with its daily supply of 40 dozen  [#permalink]

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13 Aug 2012, 06:04
3
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Difficulty:

5% (low)

Question Stats:

97% (00:51) correct 3% (01:21) wrong based on 2125 sessions

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A bakery opened yesterday with its daily supply of 40 dozen rolls. Half of the rolls were sold by noon, and 80 percent of the remaining rolls were sold between noon and closing time. How many dozen rolls had not been sold when the bakery closed yesterday?

(A) 1
(B) 2
(C) 3
(D) 4
(E) 5

Practice Questions
Question: 19
Page: 154
Difficulty: 550

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Posts: 61385
Re: A bakery opened yesterday with its daily supply of 40 dozen  [#permalink]

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13 Aug 2012, 06:04
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SOLUTION

A bakery opened yesterday with its daily supply of 40 dozen rolls. Half of the rolls were sold by noon, and 80 percent of the remaining rolls were sold between noon and closing time. How many dozen rolls had not been sold when the bakery closed yesterday?

(A) 1
(B) 2
(C) 3
(D) 4
(E) 5

20 rolls were sold sold by noon and 80% of the remaining 20 rolls were sold between noon and closing time, thus only 20% of these remaining 20 rolls had not been sold when the bakery closed. Hence 0.2*20=4 rolls had not been sold when the bakery closed.

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Re: A bakery opened yesterday with its daily supply of 40 dozen  [#permalink]

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09 Sep 2014, 22:53
1
Bunuel wrote:
A bakery opened yesterday with its daily supply of 40 dozen rolls. Half of the rolls were sold by noon, and 80 percent of the remaining rolls were sold between noon and closing time. How many dozen rolls had not been sold when the bakery closed yesterday?

(A) 1
(B) 2
(C) 3
(D) 4
(E) 5

Practice Questions
Question: 19
Page: 154
Difficulty: 550

half of the 40 dozen roll = 20

80% of 20 = 20*0.8 = 16

20-16 =4 , which is not sold.
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Re: A bakery opened yesterday with its daily supply of 40 dozen  [#permalink]

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13 Aug 2012, 07:18
answer is D ...4 dozens ....

half sold by noon --> 20 dozens (20 *12 =240)
remaining --> 20 dozens i.e 240 eggs...
80% sold --> 80*240/100 =192 eggs
remaining 20 % --> 48 eggs (4 dozens ) --> answer
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Re: A bakery opened yesterday with its daily supply of 40 dozen  [#permalink]

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13 Aug 2012, 08:21
I'm also getting D, but the OA is E. Looking forward to the explanation.
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Re: A bakery opened yesterday with its daily supply of 40 dozen  [#permalink]

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13 Aug 2012, 08:26
Answer has to be 4 dozens, May be the OA is wrong
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Re: A bakery opened yesterday with its daily supply of 40 dozen  [#permalink]

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13 Aug 2012, 09:00
ashish8 wrote:
I'm also getting D, but the OA is E. Looking forward to the explanation.

OA with a solution will be provided on Friday. E was marked there accidentally.
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Re: A bakery opened yesterday with its daily supply of 40 dozen  [#permalink]

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17 Aug 2012, 00:07
SOLUTION

A bakery opened yesterday with its daily supply of 40 dozen rolls. Half of the rolls were sold by noon, and 80 percent of the remaining rolls were sold between noon and closing time. How many dozen rolls had not been sold when the bakery closed yesterday?

(A) 1
(B) 2
(C) 3
(D) 4
(E) 5

20 rolls were sold sold by noon and 80% of the remaining 20 rolls were sold between noon and closing time, thus only 20% of these remaining 20 rolls had not been sold when the bakery closed. Hence 0.2*20=4 rolls had not been sold when the bakery closed.

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Re: A bakery opened yesterday with its daily supply of 40 dozen  [#permalink]

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02 Aug 2013, 11:56
worst question ever i thought the bakery would make rolls during the day. what kind of bakery doesn't bake their own rolls?
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Re: A bakery opened yesterday with its daily supply of 40 dozen  [#permalink]

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23 Jan 2014, 11:03
isn't 40 dozen rolls mean 40x12? If i go this bakery and say give me half a dozen rolls, they will charge me for 6 rolls. not 0.5 rolls. So the total rolls should be 40X12. half rolls sold by noon mean remaining is 20x12. 80% by closing means, 0.2x20x12 remaining = 48.

whats the trick here to choose value as 40 as a starting value for total rolls.

BTW, i choose D by ignoring "dozen" in the problem by just looking at the answer choices.
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Re: A bakery opened yesterday with its daily supply of 40 dozen  [#permalink]

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23 Jan 2014, 20:16
isn't 40 dozen rolls mean 40x12? If i go this bakery and say give me half a dozen rolls, they will charge me for 6 rolls. not 0.5 rolls. So the total rolls should be 40X12. half rolls sold by noon mean remaining is 20x12. 80% by closing means, 0.2x20x12 remaining = 48.

whats the trick here to choose value as 40 as a starting value for total rolls.

BTW, i choose D by ignoring "dozen" in the problem by just looking at the answer choices.

Read the question again: "How many dozen rolls had not been sold when the bakery closed yesterday?"

They want the answer in dozen rolls. You get the answer as 4 dozen rolls.
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Re: A bakery opened yesterday with its daily supply of 40 dozen  [#permalink]

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23 Jan 2014, 21:50
Bunuel wrote:
A bakery opened yesterday with its daily supply of 40 dozen rolls. Half of the rolls were sold by noon, and 80 percent of the remaining rolls were sold between noon and closing time. How many dozen rolls had not been sold when the bakery closed yesterday?

(A) 1
(B) 2
(C) 3
(D) 4
(E) 5

Practice Questions
Question: 19
Page: 154
Difficulty: 550

40/2 * 20/100 = 4

Option D
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Re: A bakery opened yesterday with its daily supply of 40 dozen  [#permalink]

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15 Nov 2014, 02:17
20*12 sold by noon
(20/5*4)* 12= 16*12 sold by closing time (4/5 is 80%)
(20+16)*12= 36*12 sold
4*12 left = 4 dozen
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Re: A bakery opened yesterday with its daily supply of 40 dozen  [#permalink]

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11 Jan 2015, 08:27
Yes the "trick" is that they ask for dozen rolls. It is logical to calculaye the 40 dozens in the begining. And since it goes on exlpaining how many of the "rolls" were sold during the day, you sort of forget that it asks about dozens again in the end.

But still, if you do 48/12= 4, you end up with the correct answer.
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Re: A bakery opened yesterday with its daily supply of 40 dozen  [#permalink]

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21 Dec 2015, 08:08
easy question.

50% --> 20,
80% of 20 = 16.

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Re: A bakery opened yesterday with its daily supply of 40 dozen  [#permalink]

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24 May 2016, 09:44
Bunuel wrote:
A bakery opened yesterday with its daily supply of 40 dozen rolls. Half of the rolls were sold by noon, and 80 percent of the remaining rolls were sold between noon and closing time. How many dozen rolls had not been sold when the bakery closed yesterday?

(A) 1
(B) 2
(C) 3
(D) 4
(E) 5

The bakery began the day with 40 dozen rolls. Half of the rolls were sold by noon, so we know by noon we had 40 x ½ = 20 dozen rolls sold. It follows that there were 20 dozen rolls remaining between noon and closing time.

We are next given that 80% of the remaining rolls were sold between noon and closing time. Since 80% were sold, 20% were left. This means:

rolls left when the bakery closed = 0.2 x 20 = 4 dozen rolls

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Re: A bakery opened yesterday with its daily supply of 40 dozen  [#permalink]

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05 Jul 2016, 03:13
Bunuel wrote:
A bakery opened yesterday with its daily supply of 40 dozen rolls. Half of the rolls were sold by noon, and 80 percent of the remaining rolls were sold between noon and closing time. How many dozen rolls had not been sold when the bakery closed yesterday?

(A) 1
(B) 2
(C) 3
(D) 4
(E) 5

Practice Questions
Question: 19
Page: 154
Difficulty: 550

40*50%=20
20*80%=16

20-16=4
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Re: A bakery opened yesterday with its daily supply of 40 dozen  [#permalink]

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31 Oct 2018, 23:31
A half dozen was sold by noon = 40/2 = 20
The remaining half dozen = 20
Now, 80% of the remaining half dozen is also sold = 80%*20 = 16dozen
How many were not sold?

We had total = 20 = 100%
80% were sold = -80%
Remaining = 20%

100% of 20 = 20
10% of 20 = 2
20% of 20 = 4 i.e. 2+2

Re: A bakery opened yesterday with its daily supply of 40 dozen   [#permalink] 31 Oct 2018, 23:31
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