Suppose that f(x) is the (continuous) probability density function for heights of American men, in inches, and suppose that f(69) = 0.19. Think carefully about what the meaning of this mathematical statement is.(a) Approximately what percent of American men are between 68.8 and 69.2 inches tall?(b) Suppose F(h) is the cumulative distribution function of f. If F(69) = 0.5, estimate each of:F(68.8) =F(68.6) =

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Answer:

(a) 7.6%

(b) 46.2%    42.4%

Step-by-step explanation:

(a)According to the definition of Continuous probability distribution

[tex]f(x) = \frac{d}{dx}F(x)[/tex]

[tex]f(x) = \frac{F(x + h) - F(x - h)}{(x + h) - (x - h)}[/tex]

[tex]f(69) = \frac{F(69 + 0.2) - F(69 - 0.2)}{0.4}[/tex]

⇒ 0.19 × 0.4 = F(69.2) - F(68.8)

⇒ F(69.2) - F(68.8) = 0.076

⇒ 7.6%

(b) Given F(69) = 0.5

[tex]f(x) = \frac{d}{dx}F(x)[/tex]

[tex]f(x) = \frac{F(x) - F(x - h)}{x - (x - h)}[/tex]

[tex]f(69) = \frac{F(69) - F(69 - 0.2)}{0.2}[/tex]

⇒ 0.19 × 0.2 = F(69) - F(68.8)

⇒ F(68.8) = 0.5 - 0.038 = 0.462

⇒ 46.2%

[tex]f(x) = \frac{d}{dx}F(x)[/tex]

[tex]f(x) = \frac{F(x) - F(x - h)}{x - (x - h)}[/tex]

[tex]f(69) = \frac{F(69) - F(69 - 0.4)}{0.4}[/tex]

⇒ 0.19 × 0.4 = F(69) - F(68.8)

⇒ F(68.8) = 0.5 - 0.076 = 0.424

⇒ 42.4%

Part(a): Therefore, there is 7.6% of American men between 68.8 and 69.2 inches.

Part(b): The required values are,

[tex]f(68.8)=46.2\%[/tex]

[tex]f(68.8)=42.4\%[/tex]

Probability density function:

The Probability Density Function(PDF) defines the probability function representing the density of a continuous random variable lying between a specific range of values.

Part(a):

Calculate the percentage of American men are between 68.8 and 69.2 inches tall.

[tex]f(68.8\le f(x)\le69.2)=f(69.2)-f(68.8)\\=[F(69)+(dx)f(69)]-[F(69)-(dx)f(69)]\\=[0.5+(0.2\times 0.19)]-[0.5-(0.2\times 0.19)]\\=0.076\\=7.6\%[/tex]

Part(b):

Calculating [tex]F(68.8)[/tex]

[tex]f(68.8)=[F(69)-(dx)f(69)]\\=[0.5-(0.2\times 0.19)]\\=0.462\\=46.2\%[/tex]

Now, calculating [tex]f(68.6)[/tex]

[tex]f(68.6)=[F(69)-(dx)f(69)]\\=[0.5-(0.4\times 0.19)]\\=0.424\\=42.4\%[/tex]

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