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In a group of 800 people, 1/5 play at least one instrument..

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In a group of 800 people, 1/5 play at least one instrument..  [#permalink]

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New post Updated on: 05 Aug 2012, 16:58
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In a group of 800 people, 1/5 play at least one instrument, 96 play two or more. What is the probability that one student play exactly one instrument?

A) 2/125
B) 3/125
C)2/25
D) 3/25
E) 1/5

Originally posted by ferrarih on 05 Aug 2012, 08:00.
Last edited by ferrarih on 05 Aug 2012, 16:58, edited 2 times in total.
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Re: In a group with 800 people...  [#permalink]

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New post 05 Aug 2012, 08:08
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ferrarih wrote:
In a grouup of 800 people, 1/5 play at least one instrument, 96 play two or more. Whats it is e probability that one student play exactly one instrument?

A) 2/125
B) 3/125
C)2/25
D) 3/25
E) 1/5


Given that 1/5*800=160 students play 1 or more instrument and 96 play 2 or more, so 160-96=64 students play exactly 1 instrument.

Therefore the probability that a randomly chosen student plays exactly one instrument is 64/800=2/25.

Answer: C.
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Re: In a group with 800 people...  [#permalink]

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New post 05 Aug 2012, 08:14
ferrarih wrote:
In a grouup of 800 people, 1/5 play at least one instrument, 96 play two or more. Whats it is e probability that one student play exactly one instrument?

A) 2/125
B) 3/125
C)2/25
D) 3/25
E) 1/5


P(playing 2 or more instruments) = 96/800 = 3/25.
Then, the probability of playing exactly one instrument is given by:
P(playing 1 or more instruments) - P(playing 2 or more instruments) = 1/5 - 3/25 = 2/25.

Answer C.
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Re: In a group of 800 people, 1/5 play at least one instrument..  [#permalink]

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Re: In a group of 800 people, 1/5 play at least one instrument..  [#permalink]

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New post 15 Sep 2017, 10:44
Given that 1/5*800=160 students play 1 or more instrument

96 play 2 or more,

Therefore, 160-96=64 students play exactly 1 instrument.

Therefore, the probability that a randomly chosen student plays exactly one instrument is 64/800=2/25.
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Re: In a group of 800 people, 1/5 play at least one instrument..  [#permalink]

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New post 15 Sep 2017, 12:36
1/5th of the 800 students play at least one instrument = 1/5*800 = 160
96 played two or more.
No of students that played exactly one = 160-96= 64

P(E)= 64/160 = 2/25 (C)
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In a group of 800 people, 1/5 play at least one instrument..  [#permalink]

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New post 24 Oct 2018, 08:34
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ferrarih wrote:
In a group of 800 people, 1/5 play at least one instrument, 96 play two or more. What is the probability that one student play exactly one instrument?

A) 2/125
B) 3/125
C)2/25
D) 3/25
E) 1/5


OA:C

No. of Students play 1 instrument +No. of Students play 2 instruments +No. of Students play 3 instruments +...................\(= \frac{1}{5}*800 =160\)

No. of Students play 2 instrument +No. of Students play 3 instruments +No. of Students play 4 instruments +...................\(= 96\)

No of Student play exactly 1 instrument \(= 160-96=64\)

probability that one student play exactly one instrument \(= \frac{64}{800}=\frac{2}{25}\)
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Re: In a group of 800 people, 1/5 play at least one instrument..  [#permalink]

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New post 25 Oct 2018, 17:53
ferrarih wrote:
In a group of 800 people, 1/5 play at least one instrument, 96 play two or more. What is the probability that one student play exactly one instrument?

A) 2/125
B) 3/125
C)2/25
D) 3/25
E) 1/5


We see that 1/5 x 800 = 160 people play at least one instrument.

Since 96 people play two or more instruments, then 160 - 96 = 64 play exactly one.

So the probability that a student plays exactly one instrument is 64/800 = 8/100 = 2/25.

Answer: C
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Re: In a group of 800 people, 1/5 play at least one instrument..   [#permalink] 25 Oct 2018, 17:53
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