Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized for You
we will pick new questions that match your level based on your Timer History
Track Your Progress
every week, we’ll send you an estimated GRE score based on your performance
Practice Pays
we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:
Your score will improve and your results will be more realistic
Is there something wrong with our timer?Let us know!
Thirty airmail and 40 ordinary envelopes are the only envelo
[#permalink]
06 May 2019, 10:37
1
Expert Reply
00:00
Question Stats:
38% (01:31) correct
61% (03:17) wrong based on 18 sessions
HideShow
timer Statistics
Thirty airmail and 40 ordinary envelopes are the only envelopes in a bag. Thirty-five envelopes in the bag are unstamped, and \(\frac{5}{7}\) of the unstamped envelopes are airmail letters. What is the probability that an envelope picked randomly from the bag is an unstamped airmail envelope?
Re: Thirty airmail and 40 ordinary envelopes are the only envelo
[#permalink]
02 Feb 2021, 00:18
Carcass wrote:
Thirty airmail and 40 ordinary envelopes are the only envelopes in a bag. Thirty-five envelopes in the bag are unstamped, and \(\frac{5}{7}\) of the unstamped envelopes are airmail letters. What is the probability that an envelope picked randomly from the bag is an unstamped airmail envelope?
(A) \(\frac{1}{7}\)
(B) \(\frac{1}{3}\)
(C) \(\frac{13}{35}\)
(D) \(\frac{17}{38}\)
(E) \(\frac{23}{70}\)
Carcass, by any chance, was it unstamped-ordinary envelopes in the question?
_________________
Re: Thirty airmail and 40 ordinary envelopes are the only envelo
[#permalink]
02 Feb 2021, 02:37
Carcass wrote:
sorry Sir
what do you mean?
I mean that instead of "What is the probability that an envelope picked randomly from the bag is an unstamped airmail envelope?" don't you think it should be "What is the probability that an envelope picked randomly from the bag is an unstamped ordinary envelope?" to get 1/7 as the answer?
_________________
Thirty airmail and 40 ordinary envelopes are the only envelo
[#permalink]
27 Aug 2022, 00:17
I got \(\frac{5}{14}\) as well
\(\frac{5}{7}*35 =25\) are unstamped airmail envelopes.
the probability that an envelope picked randomly from the bag is an unstamped airmail envelope \(\frac{25}{70}\) is simplified to\( \frac{5}{14}\)
While, finding the probability that an envelope picked randomly from the bag is an unstamped ordinary envelope would be \(35-25 = 10\) are unstamped ordinary envelopes, so the probability of picking randomly is\( \frac{10}{70} = \frac{1}{7} \)and this is could match with the correct answer.
Thirty airmail and 40 ordinary envelopes are the only envelo
[#permalink]
27 Aug 2022, 02:00
Expert Reply
The question as per the book is correct
OE
Quote:
We have that 30 airmail and 40 ordinary envelopes are the only envelopes in the bag. Hence, the total number of envelopes is 30 + 40 = 70. We also have that 35 envelopes in the bag are unstamped, and 5/7 of these envelopes are airmail letters. Now, 5/7 * 35 = 25. So the remaining 35 – 25 = 10 are ordinary unstamped envelopes. Hence, the probability of picking such an envelope from the bag is
(Number of unstamped ordinary envelopes) / (Total number of envelopes) = 10/70 = 1/7