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# 請問Theory is the study 意思

investigated the interaction between organisms and their environment, and the ways this relationship depends on geography—laying the foundations for biogeography, ecology and ethology. Naturalists began to reject essentialism and consider the importance of extinction and the mutability of species. Cell theory provided a new perspective on the fundamental basis of life. These developments, as well as the results from embryology and paleontology, were synthesized in Charles Darwin's theory of evolution by natural selection. The end of the 19th century saw the fall of spontaneous generation and the rise of the germ theory of disease, though the mechanism of inheritance remained a mystery.[9][10][7]

In the early 20th century, the rediscovery of Mendel's work led to the rapid development of genetics by Thomas Hunt Morgan and his students, and by the 1930s the combination of population genetics and natural selection in the "neo-Darwinian synthesis". New disciplines developed rapidly, especially after Watson and Crick proposed the structure of DNA. Following the establishment of the Central Dogma and the cracking of the genetic code, biology was largely split between organismal biology—the fields that deal with whole organisms and groups of

三、According to a report issued by the Food and Drug Association (FDA) of US, total protein consumed per day by adults of age between 18 to 30 years are approximately normally distributed with a mean of 150mg and a standard deviation of 20mg.

1. What is P( ＞140) based on a random sample of 5 adults from this population?

2. What is P(155＜ ＜160) based on a random sample of 20 adults from this population?

3. Find the value of Y so that P(150＜ ＜Y)=0.2 based on a random sample of 36 adults from this population.

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### 1 Answer

- 俏鬍子Lv 41 decade agoFavorite Answer
母體分配 Xi～N( 150，202)

1. 抽樣分配 X-bar～N( 150，202/5)，其中 X-bar = ΣXi/n，i = 1，2，…，n。n = 5

P( X-bar > 140 )

140 – 150

= P( Z > -------------- )

√(202/5)

= P( Z > -1.1180 )

= 0.8682

2. 抽樣分配 X-bar～N( 150，202/20)，其中 X-bar = ΣXi/n，i = 1，2，…，n。n = 20

P( 155 < X-bar < 160 )

= P( X-bar < 160 ) – P( X-bar < 155 )

160 – 150 155 – 150

= P( Z < ---------------- ) - P( Z < ------------------ )

√(202/20) √(202/20)

= P( Z < 2.2361 ) - P( Z < 1.1180 )

= 0.9873 - 0.8682

= 0.1191

3. 抽樣分配 X-bar～N( 150，202/36)，其中 X-bar = ΣXi/n，i = 1，2，…，n。n = 36

P( 150 < X-bar < Y )

= P( X-bar < Y ) – P( X-bar < 150 )

Y – 150 150 – 150

= P( Z < --------------- ) - P( Z < ----------------- )

√(202/36) √(202/36)

= P( Z < 0.5244 ) - P( Z < 0 )

= 0.7 – 0.5

= 0.2

∴ Y = 150 √(202/36) 0.5244 = 151.7480

Source(s): 我的求學過程…