Question

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) =

Answer 1

Answer:

(a) 7.6%

(b) 46.2%    42.4%

Step-by-step explanation:

(a)According to the definition of Continuous probability distribution

$f(x) = \frac{d}{dx}F(x)$

$f(x) = \frac{F(x + h) - F(x - h)}{(x + h) - (x - h)}$

$f(69) = \frac{F(69 + 0.2) - F(69 - 0.2)}{0.4}$

⇒ 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

$f(x) = \frac{d}{dx}F(x)$

$f(x) = \frac{F(x) - F(x - h)}{x - (x - h)}$

$f(69) = \frac{F(69) - F(69 - 0.2)}{0.2}$

⇒ 0.19 × 0.2 = F(69) - F(68.8)

⇒ F(68.8) = 0.5 - 0.038 = 0.462

⇒ 46.2%

$f(x) = \frac{d}{dx}F(x)$

$f(x) = \frac{F(x) - F(x - h)}{x - (x - h)}$

$f(69) = \frac{F(69) - F(69 - 0.4)}{0.4}$

⇒ 0.19 × 0.4 = F(69) - F(68.8)

⇒ F(68.8) = 0.5 - 0.076 = 0.424

⇒ 42.4%