Suppose that the distance of fly balls hit to the outfield (in baseball) is normally distributed with a mean of 250 feet and a standard deviation of 50 feet.

a. If X = distance in feet for a fly ball, then X ~ _____(_____,_____)

b. If one fly ball is randomly chosen from this distribution, what is the probability that this ball traveled fewer than 220 feet? Sketch the graph. Scale the horizontal axis X. Shade the region corresponding to the probability. Find the probability.

c. Find the 80th percentile of the distribution of fly balls. Sketch the graph, and write the probability statement.

Short Answer

Expert verified
  1. If X=distance in feet for a fly ball, then X~N(250,50).
  2. The probability that a randomly selected fly ball traveled fewer than 220 feet is given by P(x<220)=0.2743.
  3. The 80th percentile of the distribution of fly balls is 292.08.

Step by step solution

01

Part (a) Step 1: Given Information 

Given in the question that, the distance of fly balls hit to the outfield (in baseball) is normally distributed with a mean of 250 feet and a standard deviation of 50 feet.

02

Part(a) Step 2: Explanation 

Xis a random variable with a mean of 250and a standard deviation of 50that represents the distance of fly balls hit to the outfield in baseball. If a random variable Xhas a normal distribution with a mean of μand a standard deviation of s, it is denoted as X~N(μ,s). As a result, the random variable Xin this situation is denoted as:X~N(250,50)

03

Part(b) Step 2: Explanation 

Given that the distance (X) of fly balls hit to the outfield is such that X~N(250,50), we must calculate the probability that a randomly selected fly ball went less than 220 feet.

04

Part (b) Step 2: Explanation 

According to the information, we know that X~N(250,50)

Here,

μ=250s=50

Let's take z=x-μσ

The chance that a randomly chosen fly ball will go less than 220 feet is calculated as follows:

P(x<220)=Px-μσ<220-25050=P(z<-0.6)

The shaded zone in the graph below depicts the needed probability. As a result, it can be written:

P(z<-0.6)=0.5-P(-0.6z0)=0.5

Due to symmetry:

-P(0z0.6)=0.5

From normal table: -0.2258=0.2743

05

Part (c) Step 1: Given Information 

Given that the distance (X) of fly balls hit to the outfield is such that X~N(250,50), the 80th percentile of the distribution of fly balls.

06

Part(c) Step 2: Explanation 

The needed probability is calculated as follows:

P(x<k)=Px-μσ<k-25050=Pz<z1=0.8

We can deduce the following from the normal distribution tables:

z1=0.8416

In the equation, x=μ+zσreplace xwith kand z1, we get

k=250+0.8416*50=292.08

The following graph depicts the corresponding region:

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