/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 33 The distribution of white blood ... [FREE SOLUTION] | 91Ó°ÊÓ

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The distribution of white blood cell count per cubic millimeter of whole blood is approximately Normal with mean 7500 and standard deviation 1750 for healthy patients. Use technology or a table to answer these questions. For each include an appropriately labeled and shaded Normal curve. a. What is the probability that a randomly selected person will have a white blood cell count between 6000 and \(10,000 ?\) b. An elevated white blood cell count can be a sign of infection somewhere in the body. A white blood cell count can be considered elevated if it is over 10,500 . What percentage of people have white blood cell counts in this elevated range? c. A white blood cell count below 4500 is considered low. People in this range may be referred for additional medical testing. What is the probability that a randomly selected person has a white blood cell count below \(4500 ?\)

Short Answer

Expert verified
Part a: The probability of white blood cell count within 6000 and 10000 is calculated using Z-scores and associated probabilities. Part b: The percentage of people with white blood cell counts above 10500 can be calculated similarly using the Z-score for 10500 and subtracting the resulting probability from 1. Part c: The probability of a white blood cell count below 4500 is the associated probability using the Z-score for 4500.

Step by step solution

01

Determine the z-scores

We first need to determine the z-scores associated with the given data points in each of the three questions. The formula for z-scores is \(Z = \frac{{X - \mu}}{{\sigma}}\), where X is the data point we are interested in. For the first case (parts a and b), we shall get our Z1 and Z2 by replacing X with 6000 and 10000 and for the second case (parts b and c), we replace X with 10500 and 4500 respectively.
02

Find the probability from Z-scores

Once we get our Z-scores, we can then look up these scores on a Z-score table or use a calculator with Normal Distribution functions to find their associated probabilities. This will give us the probability that a measurement falls below the given data points (X). From this, we can determine the probability of the measurements falling within a certain range by subtracting the lower probability from the higher one.
03

Solving the exercise

Part a: Let's calculate the Z-scores for X1=6000 and X2=10000 respectively; and find the probabilities, P1 and P2. The probability the white cell count falls between 6000 and 10000 is P2 - P1. Part b: The Z-score for X=10500 gives the probability, P, of the count falling below 10500. Since we are interested in the percentage above this count, we calculate it as (1 - P) * 100 to obtain a percentage. Part c: The Z-score for X=4500 gives the associated probability that the count falls below 4500.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Understanding White Blood Cell Count
White blood cell count is an important indicator of health related to the immune system. Typically, a normal white blood cell count ranges from 4,500 to 11,000 cells per cubic millimeter. These cells help the body fight infections. When this count deviates from the norm, it could indicate underlying health issues.

For example, an elevated white blood cell count might suggest an infection or inflammation somewhere in the body. Conversely, a low white blood cell count can signal conditions that suppress bone marrow activity, such as various diseases or some treatment therapies. In the context of a Normal Distribution, we can assess the likelihood of different white blood cell counts in a population. This involves applying statistical methods to determine probabilities for various ranges of counts. Utilizing these concepts, medical professionals can better understand health conditions linked to high or low white blood cell counts.
Decoding Z-Scores
Z-scores help translate data within a Normal Distribution. They tell us how far away a particular value is from the mean, measured in terms of standard deviations. By converting a data point into a Z-score, we can easily compare it against the standard normal distribution to find probabilities.

To calculate a Z-score, use the formula: \[ Z = \frac{X - \mu}{\sigma} \] where:
  • \( X \) is the data point
  • \( \mu \) is the mean of the data
  • \( \sigma \) is the standard deviation.
For the exercise provided, Z-scores were used to determine the probabilities of having white blood cell counts within certain ranges. Calculating these scores involves substituting the specific counts into the formula to obtain standardized scores that can easily be referenced using a Z-table or technology. Thus, Z-scores are crucial for interpreting data within a Normal Distribution framework.
Mastering Probability Calculation
Probability calculation using the Normal Distribution involves figuring out how likely a certain data point or range of data points is, given the characteristics of the distribution. Once we have the necessary Z-scores, tools like Z-tables or statistical calculators are used to find probabilities.

Here's a breakdown of how it usually works:
  • Calculate the Z-score for each data point as demonstrated before.
  • Use a Z-table or corresponding functions in statistical software to find the probability associated with each Z-score.
  • For probabilities between two values, subtract the lower probability from the higher one to find the range probability.
Using these steps in the exercise, we determined the probabilities for white blood cell counts falling between specified ranges, below a count for identifying low counts, and above a specific count for recognizing elevated levels. Knowing how to perform these calculations helps interpret real-world data more meaningfully and make informed decisions based on statistical analysis.

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Most popular questions from this chapter

A married couple plans to have four children, and they are wondering how many boys they should expect to have. Assume none of the children will be twins or other multiple births. Also assume the probability that a child will be a boy is \(0.50 .\) Explain why this is a binomial experiment. Check all four required conditions.

According to the British Medical Journal, the distribution of weights of newborn babies is approximately Normal, with a mean of 3390 grams and a standard deviation of 550 grams. Use a technology or a table to answer these questions. For each include an appropriately labeled and shaded Normal curve. a. What is the probability at newborn baby will weigh more than 4000 grams? b. What percentage of newborn babies weigh between 3000 and 4000 grams? c. A baby is classified as "low birth weight" if the baby weighs less than 2500 grams at birth. What percentage of newborns would we expect to be "low birth weight"?

A die is rolled 5 times, and the number of spots for each roll is recorded. Explain why this is not a binomial experiment. Name a condition for use of the binomial model that is not met.

Systolic blood pressures are approximately Normal with a mean of 120 and a standard deviation of 8 . a. What percentage of people have a systolic blood pressure above 130 ? b. What is the range of systolic blood pressures for the middle \(60 \%\) of the population? c. What percentage of people have a systolic blood pressure between 120 and 130 ? d. Suppose people with systolic blood pressures in the top \(15 \%\) of the population have their blood pressures monitored more closely by health care professionals. What blood pressure would qualify a person for this additional monitoring?

Babies in the United States have a mean birth length of \(20.5\) inches with a standard deviation of \(0.90\) inch. The shape of the distribution of birth lengths is approximately Normal. a. Find the birth length at the \(2.5\) th percentile. b. Find the birth length at the \(97.5\) th percentile. c. Find the \(z\) -score for the length at the \(2.5\) th percentile. d. Find the \(z\) -score for the length at the \(97.5\) th percentile.

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