Question from Challenge 7

Question

Please explain your answers


If 40% of unsuccessful suicide attempts are repeated within 6 months and 25% of suicides are successful, what percentage of suicides in any 6 months period is the first attempt?

(A) 30
(B) 40
(C) 50
(D) 60
(E) 70

allabout · Answer

is there some information missing?

manish8109 · Answer

assume no. of suicide attempts be x

 successful suicide attempts in 6 month period =25x/100
 unsuccessful suicide attempts=75x/100
 repeated suicide attempts of unsuccessful suicides=75x/100 *40/100
 =3x/10
 new suicide attempts every month=x-3x/10=7x/10 that implies to 70%(ans)

razrulz · Answer

excellent approach.. can u explain the reason for the last step pls.

chuckle · Answer

Going by the same logic as Manish,
Successful attempts = 25%
=> Unsuccessful attempts = 75%
% of Unsuccessful attempts that repeat within 6 months = 40%
=> At any given point of time, total % of repetitions = (75/100)*(40/100)
 = 30/100 = 30%
=> At any given point of time, number of first attempts = 70%

chiragr · Answer

could not solve quesiton as I feel some information is missing.. OA/OE

chirag

Professor · Answer

suppose total sucide attempts = 100%
sucessful = 25%
unsuccessful = 75%
repeate = 40% of unsuccessful=40% of 75% = 30%
so every month 30% sucide attempts are repeate. therefore, first attemp = 100%-30%=70%

razrulz · Answer

Yes Prof, thnks.. got it

shiboni · Answer

i understand the explanations given above, but what about the successful attempts in that six month period that are not first attempts? couldn't some of those be repeats of people who failed the first time? that would make the answer less than 70% i feel the question needs to clarify this...

dukapotamus · Answer

Well, I have a little different thought process here and wanted to put it out there. Any takers /thoughts ?

The solution might be clearer once we divide the explanation into two parts - 

Part I - First Attempts:

For any month, 100% of original attempts are first attempts.


Part II - Second Attempts:

40% of failed attempts (= 75 % of original attempts) are attempted again => (40/100) * (75/100) = 3/10 = 30%

This 30% is the percentage which denotes "The percentage of the UNSUCCESSFUL attempts which are tried again". And NOT, "the percentage of ALL attempts". 

So, from part 1, we get 25% or 1/4
and from part 2, we get 30% or 3/10.

Now, the question is "What percentage of ALL the attempts are first attempts" ?

ALL attempts = Original attempts (all these are first attempts) + Retry attempts
 = 100 + 30 = 130%.

Percentage of First attempts from ALL attempts = 100/130 = 77% (which is not in the answer choice listed).

Did I over analyze too much, but logically, sounds right.

For example, if 40 attempts were made. 10 were good and 30 were bad. Out of these bad attempts, 40% were tried again = 0.4 * 30 = 12 attempts were retried. So, total attempts = 40 + 12.

Percentage of First attempts from ALL attempts = 40/52 = 77 %.

(Using the example above)Obviously, the question didn't say/mean that the 40 attempts included the retry attempts as well. If it did, then it would be like asking the same question again and again.

chuckle · Answer

The assumption here should be that "at any time, only 40 people will attempt" i.e., what ever "n" you take as the total attempt, that remains the same (constant), otherwise, there is no solution to this.

El Torro · Answer

If 40% of unsuccessful suicide attempts are repeated within 6 months and 25% of suicides are successful,

I am stuck at this point. 
does the question say that the success rate is 25% for the repeated suicide attempts or that the success rate is 25% for all suicide attempts.

chuckle · Answer

You can assume the success rate is 25% for all attempts.

Praetorian · Answer

The answer is 70.

{E} Letâ€™s pick numbers to solve this problem:

Letâ€™s say 100 people commit suicides every 6 months. Out of them, 25 are successful and 75 are not. If 40% of unsuccessful attempts are repeated or 0.75*40 = 30, then 70 are new attempts every 6 months.

jlui4477 · Answer

I got E.

1) 40 attempted 2) 25% (40 attempted) = 10 succesful suicides 3) 40 attempted - 10 suicides = 30 attempted This means the rest, 70 were first-timers.

El Torro · Answer

Thanks chuckle. Just moving into this forum from the Verbal forum. I think I will have the verbal hangover for sometime.

gameCode · Answer

If 40% of unsuccessful suicide attempts are repeated within 6 months and 25% of suicides are successful, what percentage of suicides in any 6 months period is the first attempt?

30
40
50
60
70

Pls explain your answer. Thanks.

subarao · Answer

Unsuccessful suicide rate = 75%
40% of 75% i.e 40/100* 75=30% are repeated within first 6 months
So the unrepeated first attempts are =100-30= 70%
So E is the ans

What is OA?

GMAT TIGER · Answer

S = 25%
U = 75%
R = 40% of 75% = 30%

REPEATED/SUCESSFUL = 25% of 30% = 7.5% 
First attempt sucessful = 25% - 7.5% = 17.5% which is also 25% of the first attempt
so first attempt = 17.5%/0.25 = 70%

gameCode · Answer

Thanks for the reply. The QA is 70 . I got confused because i thought 25 % are unsuccessful out of the 40 % that retried. Whereas, its the 25 % of the total candicates are unsuccessful. The language in these kind of qs always confuses me.

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