14. Endangered Species The chart below shows the num- bers of endangered and thr

Question

14. Endangered Species The chart below shows the num- bers of endangered and threatened species both here in the United States and abroad. Threatened Endangered United States Foreign States Foreign United Mammals 68 Birds Reptiles Amphibians 11 20 6 16 251 175 64 10 13 14 10 Source: www.infoplease.com Choose one species at random. Find the probability that it is a. Threatened and in the United States b. An endangered foreign bird c. A mammal or a threatened foreign species 15. Multiple Births The number of multiple births in the United States for a recent year indicated that there were 128,665 sets of twins, 7110 sets of triplets, 468 sets of quadruplets, and 85 sets of quintuplets. Choose one set of siblings at random. a. Find the probability that it represented more than two babies. b. Find the probability that it represented quads or quints.

Explanation / Answer

14. The table is reproduced below with totals of different species and whether in the U.S. or foreign:

a. The probability that a randomly chosen species is threatened and is in the U.S. = (number of  species is threatened and is in the U.S.) / (total number of species) = 55 / 766 = 0.072

b. The probability that a randomly chosen species is an endangered foreign bird = 498 / 766 = 0.65

c. The probability that a randomly chosen species is a mammal or a threatened foreign species =

The probability that a randomly chosen species is a mammal + The probability that a randomly chosen species is a threatened foreign species - The probability that a randomly chosen species is a mammal AND a threatened foreign species = 349 / 766 + 43 / 766 - 20 / 766 = 372 / 766 = 0.486

Endangered Threatened Total Unites States Foreign Unites States Foreign Mammals 68 251 10 20 349 Birds 77 175 13 6 271 Reptiles 14 64 22 16 116 Amphibians 11 8 10 1 30 TOTAL 170 498 55 43 766

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