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Seminar attendance prob

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Seminar attendance prob

by selango » Mon May 24, 2010 1:11 am
GMAT PREP

At a two day seminar ,90 percent of those registered attended the seminar on the first day
what percent of those registered did not attend the seminar on either day?

A) A total of 1000 people registered for the two day seminar

B) Of those registered, 80 percent attended the seminar on second day

Pls suggest
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by liferocks » Mon May 24, 2010 1:23 am
From 1
we get 100 people did not attended the seminar on day 1,but no information on how many attended on day 2...not sufficient

From 2
we get 80% of registered attended on day 2,but no in formation on how many of the registered people attended both days..not sufficient

combining ,
does not provide any of the missing information..not sufficient

IMO ans option E
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by selango » Mon May 24, 2010 1:38 am
Pls correct me if I am wrong

Combining A and B we get

Day 1 -

total registerd - 1000

Attended - 900 Not attended - 100

Day2-

Total registered -1000

Attended - 800 Not attended -200

So combining A and B we r getting the result


Pls clarify
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by liferocks » Mon May 24, 2010 1:44 am
selango wrote:Pls correct me if I am wrong

Combining A and B we get

Day 1 -

total registerd - 1000

Attended - 900 Not attended - 100

Day2-

Total registered -1000

Attended - 800 Not attended -200

So combining A and B we r getting the result


Pls clarify
As I have mentioned ,none of the options provide any informations on how many attended on both days

ex, let 700 attended on both days

in day 1 900 attended and 100 didnt
day 2 800-700=100 attended who didn't attended day 1

so all who have registered have attended at least one day..ans is 0%

Now take 800 attended on both days
in day 1 900 attended and 100 didnt
day 2 800-800=0 attended who didn't attended day 1

so in this case ans is 100 or 10%

we need to know how many people(percentage) attended the seminar both days to ans this question.
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by selango » Mon May 24, 2010 1:54 am
We need people who did not attend the seminar on either day


Day 1 - 100

Day 2 - 200

Total 300 people did not attend the seminar on either day

So 300 is 30 % of 1000 people

pls clarify
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by liferocks » Mon May 24, 2010 2:02 am
selango wrote:We need people who did not attend the seminar on either day


Day 1 - 100

Day 2 - 200

Total 300 people did not attend the seminar on either day

So 300 is 30 % of 1000 people

pls clarify
check the line in bold. That is not correct.correct statement is 'Total 300 people did not attend the seminar on either 1 or day 2 ' .People didn't attended on either day means people who have not attended on both days not any one of the days.
Does this clarifies?
btw what is the OA?
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by selango » Mon May 24, 2010 2:07 am
oops got it

Thanks

Answer is E
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by Patrick_GMATFix » Mon May 24, 2010 11:36 am
This is GMATPrep question 1441. Please watch the step-by-step video solution if you still have trouble solving.

-Patrick
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by [email protected] » Tue May 25, 2010 3:22 am
selango wrote:GMAT PREP

At a two day seminar ,90 percent of those registered attended the seminar on the first day
what percent of those registered did not attend the seminar on either day?

A) A total of 1000 people registered for the two day seminar

B) Of those registered, 80 percent attended the seminar on second day

Pls suggest
:evil:

use the sets theory to solve this problem!!

here there are two sets that intersect: people who attended Day1 only, Day2 only and people who attended both days.

let T = total of all registered,
let z = people who attended both Day1 and Day2
let x = people who attended Day1 only then x = 0.9T - z
let y = people who attended Day2 only;

therefore, people who did attend neither days = 1000 - (x+y+z)

Statement 1:

T = 1000
x= 900 - z

insufficient

Statement 2:

y = 0.8T - z

insufficient

combine statements 1 & 2:
x = 900 - z
y = 800 - z

1000 - (x+y+z) = 1000 - (1700 - z) = z - 700

insufficient

here neither statement alone will get you an answer not the combination of both statements (i.e. C).

ANSWER is (E)
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