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# Jake remembers only the last three letters of his four-letter Klingon

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Math Expert
Joined: 02 Sep 2009
Posts: 59675
Jake remembers only the last three letters of his four-letter Klingon  [#permalink]

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20 Sep 2016, 08:30
2
13
00:00

Difficulty:

25% (medium)

Question Stats:

66% (01:14) correct 34% (01:34) wrong based on 194 sessions

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Jake remembers only the last three letters of his four-letter Klingon name. If he is sure that the first letter is neither "N" nor "Z", and assuming that there are only 10 letters in the Klingon alphabet, what is the probability that he will give the correct name when asked for it by the space attendant?

A. 8/100
B. 9/100
C. 1/8
D. 4/5
E. 9/10

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Posts: 8302
Re: Jake remembers only the last three letters of his four-letter Klingon  [#permalink]

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20 Sep 2016, 08:41
1
2
Bunuel wrote:
Jake remembers only the last three letters of his four-letter Klingon name. If he is sure that the first letter is neither "N" nor "Z", and assuming that there are only 10 letters in the Klingon alphabet, what is the probability that he will give the correct name when asked for it by the space attendant?

A. 8/100
B. 9/100
C. 1/8
D. 4/5
E. 9/10

Total letters 10, out of which the first letter is anything of 10 but N or X...
So there are 8 possible letters for first place..
And only one of them is correct..
So 1/8.. C
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Re: Jake remembers only the last three letters of his four-letter Klingon  [#permalink]

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20 Sep 2016, 11:21
This is a question about independent events.

Jake remembers the second and third letters of his Klyngon name, therefore the probability for these two letters is 1. For the first letter, he is confident that it´s neither "N" or "Z" and it is given that the total number of possible letters is 10. So, the probability of getting the first letter correctly is 1 divided by the total number of possible letters (in this case 8 because he knows that of the 10 letters there are two that cannot be)

I think the solution is C (1/8)
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Joined: 26 Jan 2016
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Re: Jake remembers only the last three letters of his four-letter Klingon  [#permalink]

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20 Sep 2016, 12:41
There are 10 letters and we can eliminate two. Because there is only 1 correct beginning letter probability is 1/8. C
Economist GMAT Tutor Representative
Joined: 06 Aug 2019
Posts: 118
Jake remembers only the last three letters of his four-letter Klingon  [#permalink]

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31 Aug 2019, 07:48
1

Official Explanation

It is usually easier to find the denominator of the probability formula first. The denominator is the total number of possible outcomes:

Probability = $$\frac{Number of wanted outcomes}{Total number of possible outcomes}$$

In this question the denominator is the total number of letters that Jake can select for the first letter, given that he knows that it is neither "N" nor "Z." Find the total number of outcomes: Jake has 8 possible choices because 2 out of the possible 10 are already ruled out. The number of wanted outcomes is the single correct letter. Therefore, the probability that he will pick it randomly is $$\frac{1}{8}$$
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Jake remembers only the last three letters of his four-letter Klingon   [#permalink] 31 Aug 2019, 07:48
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