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In a certain bookcase, 10 books are about science, 8 are about literat

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Bunuel
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In a certain bookcase, 10 books are about science, 8 are about literat [#permalink] In a certain bookcase, 10 books are about science, 8 are about literat   18 Jan 2019, 01:03
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E

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In a certain bookcase, 10 books are about science, 8 are about literature, 5 are about history, and 2 are about psychology. If a book is selected at random, what is the probability that the book is about science or history?

A 0.08
B 0.2
C 0.3
D 0.4
E 0.6
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E
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Re: In a certain bookcase, 10 books are about science, 8 are about literat [#permalink] In a certain bookcase, 10 books are about science, 8 are about literat   18 Jan 2019, 06:09
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Bunuel
In a certain bookcase, 10 books are about science, 8 are about literature, 5 are about history, and 2 are about psychology. If a book is selected at random, what is the probability that the book is about science or history?

A 0.08
B 0.2
C 0.3
D 0.4
E 0.6

Probability of Science of History = (Science books+History Books) / Total Books

i.e. Required Probability = (10+5) / (10+8+5+2) = 15/25 = 3/5 = 0.6

Answer: Option E
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Re: In a certain bookcase, 10 books are about science, 8 are about literat [#permalink] In a certain bookcase, 10 books are about science, 8 are about literat   18 Jan 2019, 07:39
Bunuel
In a certain bookcase, 10 books are about science, 8 are about literature, 5 are about history, and 2 are about psychology. If a book is selected at random, what is the probability that the book is about science or history?

A 0.08
B 0.2
C 0.3
D 0.4
E 0.6


total books = 25
science 10; history = 5

probability that the book is about science or history
so
10/25 + 5/25 = 15/25 = 3/5 = 0.6
IMO E
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Re: In a certain bookcase, 10 books are about science, 8 are about literat [#permalink] In a certain bookcase, 10 books are about science, 8 are about literat   12 Mar 2019, 11:49
Bunuel
In a certain bookcase, 10 books are about science, 8 are about literature, 5 are about history, and 2 are about psychology. If a book is selected at random, what is the probability that the book is about science or history?

A 0.08
B 0.2
C 0.3
D 0.4
E 0.6

A or B = A+B
So science or History 10+5

So probability:
10/25 + 5/25 = 15/25 = 3/5 = 0.6
E


P.S.- Please can we tag this question as Probability rather than Combinations
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Re: In a certain bookcase, 10 books are about science, 8 are about literat [#permalink]
12 Mar 2019, 11:49
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Bunuel
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