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# An integer is randomly chosen from 2 to 20 inclusive. What i

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GMAT Club Legend
Joined: 07 Jun 2014
Posts: 4704
GRE 1: Q167 V156
WE: Business Development (Energy and Utilities)
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Kudos [?]: 1600 [0], given: 373

An integer is randomly chosen from 2 to 20 inclusive. What i [#permalink]  05 Aug 2018, 14:23
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Question Stats:

100% (00:07) correct 0% (00:00) wrong based on 3 sessions
An integer is randomly chosen from 2 to 20 inclusive. What is the probability that the number is prime?

[Reveal] Spoiler: OA
$$\frac{8}{19}$$

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Sandy
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GMAT Club Legend
Joined: 07 Jun 2014
Posts: 4704
GRE 1: Q167 V156
WE: Business Development (Energy and Utilities)
Followers: 90

Kudos [?]: 1600 [0], given: 373

Re: An integer is randomly chosen from 2 to 20 inclusive. What i [#permalink]  07 Aug 2018, 06:05
Expert's post
Explanation

Among the integers 2 through 20, inclusive, there are 8 primes: 2, 3, 5, 7, 11, 13, 17, and 19. From 2 to 20, inclusive, there are exactly 20 – 2 + 1 = 19 integers; remember to “add one before you’re done” to include both endpoints.

Alternatively, there are 20 integers from 1 to 20, inclusive, so there must be 19 integers from 2 to 20, inclusive. Since probability is defined as the number of desired items divided by the total number of choices, the probability that the number chosen is prime is $$\frac{8}{19}$$.
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Sandy
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Re: An integer is randomly chosen from 2 to 20 inclusive. What i   [#permalink] 07 Aug 2018, 06:05
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