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btrg
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A new employee in a mobile store has been assigned to mark defective p 16 Apr 2019, 09:27
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B
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Difficulty:

95% (hard)

Question Stats:

47% (02:44) correct 53% (03:01) wrong based on 114 sessions

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A new employee in a mobile store has been assigned to mark defective pieces with red tags, and she has marked 45% of the mobile pieces defective. However, 30% of the pieces that are supposed to be marked working are now marked defective, and 40% of the pieces that are supposed to be marked defective are marked working. What percent of the pieces that are marked defective are supposed to be marked working?

A. 30%
B. 33.33%
C. 37.5%
D. 40%
E. 45%
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B
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A new employee in a mobile store has been assigned to mark defective p 16 Apr 2019, 19:29
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btrg
A new employee in a mobile store has been assigned to mark defective pieces with red tags, and she has marked 45% of the mobile pieces defective. However, 30% of the pieces that are supposed to be marked working are now marked defective, and 40% of the pieces that are supposed to be marked defective are marked working. What percent of the pieces that are marked defective are supposed to be marked working?

A. 30%
B. 33.33%
C. 37.5%
D. 40%
E. 45%
Show more

Let the number of defective and working be d and w, and total be 100, so d+w=100..
30% of the pieces that are supposed to be marked working are now marked defective, so 0.3w, and 40% of the pieces that are supposed to be marked defective are marked working, that is the remaining 60% are marked defective, so 0.6d.. Thus 0.3w+0.6d=45....3w+6d=450....w+2d=150
Subtract w+d=100 from w+2d=150.....w+2d-(w+d)=150-100...d=50..
So both w and d are 50 each...

Also, 30% of working and 60% of defective equalling 45% would mean defective=working=50% through weighted average method. (45-30)/(60-30)=1/2 or 50%

Now we have to find 'What percent of the pieces that are marked defective are supposed to be marked working' means 30% of 50 is what percent of 45.....30% of 50 = 50*(30/100)=15.. so 100*15/45=33.33%
B.
Also the conversion of such statements into equations can be done without errors by AXIOMS, a concept I think Math revolution teaches.
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A new employee in a mobile store has been assigned to mark defective p 16 Apr 2019, 19:59
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btrg
A new employee in a mobile store has been assigned to mark defective pieces with red tags, and she has marked 45% of the mobile pieces defective. However, 30% of the pieces that are supposed to be marked working are now marked defective, and 40% of the pieces that are supposed to be marked defective are marked working. What percent of the pieces that are marked defective are supposed to be marked working?

A. 30%
B. 33.33%
C. 37.5%
D. 40%
E. 45%
Show more

let total pieces = 40
45% of the mobile pieces defective = 18 pieces
30% of the pieces that are supposed to be marked working are now marked defective = .30*40 ; 12 pieces are OKAY but are marked defective
40% of the pieces that are supposed to be marked defective are marked working; .4*40 ; 16 pieces

What percent of the pieces that are marked defective are supposed to be marked working
12/18; 66.66% i.e working pieces ~33%
IMO B
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A new employee in a mobile store has been assigned to mark defective p 28 Apr 2019, 06:22
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A new employee in a mobile store has been assigned to mark defective pieces with red tags, and she has marked 45% of the mobile pieces defective. However, 30% of the pieces that are supposed to be marked working are now marked defective, and 40% of the pieces that are supposed to be marked defective are marked working. What percent of the pieces that are marked defective are supposed to be marked working?

A. 30%
B. 33.33%
C. 37.5%
D. 40%
E. 45%
Show more

Hi Bunuel can you please explain this question.
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A new employee in a mobile store has been assigned to mark defective p 08 Apr 2024, 18:10
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Total pieces = 100
The new employee has marked 45% of the mobile pieces defective. This implies that 45 are defective and 55 are working.

Now, 30% of the working are now marked defective. This implies => 0.3*55

Now, 40% of the defective are marked working. This implies => 0.4*45

Here we have to find the % of the pieces that are marked defcitve by mistake to the total defective = (0.3*55/45) * 100 %= 110/3 % = 33.33 %

Option B
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A new employee in a mobile store has been assigned to mark defective p 08 Apr 2024, 22:47
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@btrgGiven: A new employee in a mobile store has been assigned to mark defective pieces with red tags, and she has marked 45% of the mobile pieces defective. However, 30% of the pieces that are supposed to be marked working are now marked defective, and 40% of the pieces that are supposed to be marked defective are marked working.

Asked: What percent of the pieces that are marked defective are supposed to be marked working?
A new employee in a mobile store has been assigned to mark defective pieces with red tags, and she has marked 45% of the mobile pieces defective.

DefectiveWorkingTotal
Marked defective45%
Marked working100%-45%=55%
Total 100%

However, 30% of the pieces that are supposed to be marked working are now marked defective

DefectiveWorkingTotal
Marked defective45%-.3x%30%*x%=.3x%45%
Marked working.7x%55%
Total 100%-x%x%100%

40% of the pieces that are supposed to be marked defective are marked working.

​​​​​​​​​​​​​​
DefectiveWorkingTotal
Marked defective45%-.3x%30%*x%=.3x%45%
Marked working.4(100%-x%)= 40%-.4x%.7x%55%
Total 100%-x%x%100%

40% - .4x% + .7x% = 55%
.3x% = 15%
x% = 50%


​​​​​​​​​​​​​​
DefectiveWorkingTotal
Marked defective30%15%45%
Marked working20%35%55%
Total 50%50%100%

The percent of the pieces that are marked defective are supposed to be marked working = 15%/45% = 33.33%

​​​​​​​IMO B
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A new employee in a mobile store has been assigned to mark defective p 09 Feb 2025, 06:54
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Assume total = 100
Actual: working = a, defect = 100 - a
Employ: working = 55, defect = 45
0.3a move from w to d AND 0.4(100-a) move from d to w
→ a - 0.3a + 0.4(100-a) = 55 → a = 50
Q: What percent of the pieces that are marked defective (45) are supposed to be marked working (0.3a) → 15/45 = 1/3
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A new employee in a mobile store has been assigned to mark defective p 12 Aug 2026, 08:51
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Marked defectiveNot marked defectiveTotal
Actually defective6b4b10b
Working (not actually defective)3a7a10a
Total4555100

Question: What percent of the pieces that are marked defective are supposed to be marked working?

i.e., we need to find (3a)/45 as a %.

(1) 10a + 10b = 100

=> a + b = 10
=> 6a + 6b = 60

(2) 3a + 6b = 45

From (1) and (2) ->

3a = 15
=> a = 5

Our Answer: (3a)/45 -> 1/3 -> 33.33%. Choice B.

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