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service errors rate

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Master | Next Rank: 500 Posts
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by Xbond » Wed Jun 10, 2009 12:22 pm
Hi there,

I don't understand to this question. I don't know how to start. Many thks to explain the concept and reasoning the most simplest

In 1995 Division A of Company X had 4 850 customers. if there were 86 service errors in Division A that year was the service-error rate, in number of service errors per 100 customers, for Division B of company X in 1995 ?

(1) In 1995, the overall service error rate for Divisions A and B combined was 1.5 service errors per 100 customers

(2) In 1995 Division B had 9 350 customers, one of whom were customers of Division A


Answer C
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Source: — Data Sufficiency |
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by tohellandback » Wed Jun 10, 2009 8:06 pm
are you sure you have typed the question correctly. It looks awkward
The powers of two are bloody impolite!!
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by Xbond » Thu Jun 11, 2009 12:03 pm
Yes, you're right. I fix it now :


In 1995 Division A of Company X had 4 850 customers. if there were 86 service errors in Division A that year, what was the service-error rate, in number of service errors per 100 customers, for Division B of company X in 1995 ?

(1) In 1995, the overall service-error rate for Divisions A and B combined was 1.5 service errors per 100 customers

(2) In 1995 Division B had 9 350 customers, none of whom were customers of Division A
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by TBombadill » Sun Jun 21, 2009 3:10 pm
Hi, got the same doubt with this one.
Thx!
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by rahulg83 » Mon Jun 22, 2009 12:23 am
I think that when you look at the question for the first time, you'll feel statement 1 is sufficient.

86*100/4850 + (service error rate of dep B) = 1.5

But on reading statement 2, you can realize that what if the two divisions have some common customers. In that case statement 1 would be insufficient. We can't assume that customers in two departments are mutually exclusive.

Good question..
Hope that helps!!
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by pops » Mon Jun 22, 2009 1:57 am
statement 1 alone: Insufficient since we need number of customers of Division B.

statement 2 alone: Insufficient since we dont have any clue for errors in company B.

Together, statement 1 and 2:
Total number of customers A+B = 4850+9350
service errors per 100 customers = 1.5
=> Number of errors in A + B = (4850+9350)*1.5
=> Number of errors in B = (4850+9350)*1.5 - 86
[Number of errors in A + B minus Number of errors in A]

Hence, you get an answer using both statements.
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