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In a factory that produces computer circuit boards, 4.5 percent of all boards produced are found to be defective and are

Expert replies
by BTGmoderatorDC » Fri May 22, 2020 7:36 pm

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Answers

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B

C

D

E

Stats

Difficulty

In a factory that produces computer circuit boards, 4.5 percent of all boards produced are found to be defective and are repaired before being sold, but 10 percent of all defective boards are sold without being repaired. What percentage of boards produced in the factory are defective?

A. 4.5%
B. 5.0%
C. 6.0%
D. 10.0%
E. 14.5%


OA B

Source: Official Guide
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Source: — Problem Solving |

BTGmoderatorDC wrote:
Fri May 22, 2020 7:36 pm
In a factory that produces computer circuit boards, 4.5 percent of all boards produced are found to be defective and are repaired before being sold, but 10 percent of all defective boards are sold without being repaired. What percentage of boards produced in the factory are defective?

A. 4.5%
B. 5.0%
C. 6.0%
D. 10.0%
E. 14.5%

OA B

Source: Official Guide
Total Boards \(= X\)
Total Defective Boards \(= Y\)

Out of this \(Y\) "Defective" boards \(10\%\) "Escaped" (GIVEN) and \(90\%\) "Get caught and fixed"

We know that "Get Caught and fixed" \(= 4.5\%\) of \(X\). This implies

\(90\%\) of \(Y = 4.5\%\) of \(X\).

\(\dfrac{90}{100} \cdot Y = \dfrac{4.5}{100} \cdot X \Longrightarrow Y = 0.05 \cdot X \Longrightarrow 5\%\) of \(X\).

Hence, B
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BTGmoderatorDC wrote:
Fri May 22, 2020 7:36 pm
In a factory that produces computer circuit boards, 4.5 percent of all boards produced are found to be defective and are repaired before being sold, but 10 percent of all defective boards are sold without being repaired. What percentage of boards produced in the factory are defective?

A. 4.5%
B. 5.0%
C. 6.0%
D. 10.0%
E. 14.5%


OA B

Source: Official Guide
Solution:

Since 10 percent of all defective boards are sold without being repaired, 90 percent of all defective boards are sold after being repaired, and this number is also the 4.5 percent of all boards produced. Thus if we let d = the number of defective boards and n = the total number of boards, we have:

0.9d = 0.045n

d/n = 0.045/0.9 = 45/900 = 5/100 = 5%

Answer: B

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