A bakery opened yesterday with its daily supply of 40 dozen

Question

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

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

Bunuel · Answer

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

(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.

Answer: D.

abhi398 · Answer

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

pradeepss · Answer

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.

KarishmaB · Answer

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.

ScottTargetTestPrep · Answer

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

Answer: D

bumpbot · Answer

Automated notice from GMAT Club BumpBot: 

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

 This post was generated automatically.

A bakery opened yesterday with its daily supply of 40 dozen

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Problem Solving (PS) Questions

A bakery opened yesterday with its daily supply of 40 dozen

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards