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11 Apr 2021, 21:45
Kudos
Bookmarks
D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
35%
(medium)
Question Stats:
73% (02:02) correct
27%
(02:15)
wrong
based on 304
sessions
History
Date
Time
Result
Not Attempted Yet
There are 10 books on a shelf: 5 English books, 3 Spanish books and 2 Portuguese books. If selecting two books at random and without replacement, what is the probability of choosing 2 books in different languages?
A. 31/90
B. 3/10
C. 1/3
D. 31/45
E. 28/90
A. 31/90
B. 3/10
C. 1/3
D. 31/45
E. 28/90
18 Apr 2021, 21:15
Kudos
Bookmarks
Bunuel
ES + EP + SP = 2*5/10*3/9 + 2*5/10*2/9 + 2*3/10*2/9 = 31/45. Each time we are multiplying by 2 because each case has two ways of occurring. For example, English-Spanish can be picked as English first then Spanish as well as Spanish first then English.
Answer: D.
General Discussion
11 Apr 2021, 22:36
Kudos
Bookmarks
Bunuel
\(\frac{5_{C_1}*3_{C_1} + 3_{C_1}*2_{C_1} + 2_{C_1}*5_{C_1}}{10_{C_2}}\)
= \(\frac{31}{45}\)
OR
\(1 - \frac{5_{C_2} + 3_{C_2} + 2_{C_2}}{10_{C_2}}\)
= \(1- \frac{14}{45}\)
= \(\frac{31}{45}\)
Answer D.
