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Zorluk: OrtaBasic Probability and Counting Methods

A bookstore received a shipment of 5050 new books. Among these books, 2424 are fiction, 2020 are hardcover, and 88 are hardcover fiction books. If 11 book is selected at random from the shipment, what is the probability that the selected book is either a fiction book or a hardcover book?

  1. A
    425\frac{4}{25}
  2. B
    1425\frac{14}{25}
  3. 1825\frac{18}{25}Cevap
  4. D
    2225\frac{22}{25}
  5. E
    911\frac{9}{11}

Cevap

1825\frac{18}{25}
To find the probability that a randomly chosen book is either fiction or hardcover, calculate the total number of books satisfying at least one condition. By the Principle of Inclusion-Exclusion, the number of favorable books is 24+208=3624 + 20 - 8 = 36. Dividing this by the total of 5050 books yields 3650\frac{36}{50}, which simplifies to 1825\frac{18}{25}.

Adım Adım Çözüm

1
Identify the total number of items in the sample space and the counts for each event.
Total books N=50N = 50, Fiction N(F)=24N(F) = 24, Hardcover N(H)=20N(H) = 20, Both N(FH)=8N(F \cap H) = 8.
The sample space consists of all 50 shipment books.
2
Apply the Inclusion-Exclusion Principle to find the number of favorable outcomes.
N(FH)=N(F)+N(H)N(FH)=24+208=36N(F \cup H) = N(F) + N(H) - N(F \cap H) = 24 + 20 - 8 = 36.
Hardcover fiction books are counted in both individual totals, so their intersection must be subtracted once to avoid double-counting.
3
Calculate the probability and simplify the fraction.
P(FH)=3650=1825P(F \cup H) = \frac{36}{50} = \frac{18}{25}.
Probability is the ratio of favorable outcomes to total outcomes.

Anahtar Kavram

Probability of non-mutually exclusive events using the Addition Rule: P(AB)=P(A)+P(B)P(AB)P(A \cup B) = P(A) + P(B) - P(A \cap B).
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