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16 Apr 2019, 09:27
Kudos
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B
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Difficulty:
95%
(hard)
Question Stats:
48% (02:47) correct
52%
(02:59)
wrong
based on 103
sessions
History
Date
Time
Result
Not Attempted Yet
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%
A. 30%
B. 33.33%
C. 37.5%
D. 40%
E. 45%
16 Apr 2019, 19:29
Kudos
Bookmarks
btrg
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.
Archit3110
16 Apr 2019, 19:59
Kudos
Bookmarks
btrg
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
