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A shipment contains 9 igneous, 7 sedimentary, and 7 metamorphic rocks. If 7 rocks are selected at random, find the probability that exactly 5 are sedimentary.

Sagot :

Answer:

75 percent

Step-by-step explanation:

see the thing is

The probability that exactly 5 are sedimentary is from a shipment which contains 9 igneous, 7 sedimentary, and 7 metamorphic rocks is 21/33649.

What is combination?

Combination is the way of arrangement or the collection of items in the particular order. The order of this group of items does not matter in the combination type of arrangement.

A shipment contains 9 igneous, 7 sedimentary, and 7 metamorphic rocks. If 7 rocks are selected at random, find the probability that exactly 5 are sedimentary.

Number of ways to choose 5 sedimentary from 7  sedimentary is,

[tex]^7C_5=\dfrac{7!}{(7-5)!5!}\\^7C_5=\dfrac{7\times6\times5!}{2!5!}\\^7C_5=\dfrac{7\times6}{2\times1}\\^7C_5=21[/tex]

There are total 23 rocks (9+7+7). Number of ways to choose 7 rocks from 23 rocks is,

[tex]^{23}C_5=\dfrac{23!}{(23-5)!5!}\\^{23}C_5=\dfrac{23!}{18!5!}\\^{23}C_5=33649[/tex]


Thus, the probability that exactly 5 are sedimentary is,

[tex]P=\dfrac{21}{33649}[/tex]

Hence, the probability that exactly 5 are sedimentary is from a shipment which contains 9 igneous, 7 sedimentary, and 7 metamorphic rocks is 21/33649.

Learn more about the combination here;

https://brainly.com/question/17139330

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