Math Problem Statement

Assume that the amounts of weight that male college students gain during their freshman year are normally distributed with a mean of mu equals 1.1 kg and a standard deviation of sigma equals 4.6 kg. Complete parts​ (a) through​ (c) below.

a. If 1 male college student is randomly​ selected, find the probability that he gains between 0 kg and 3 kg during freshman year.

The probability is

Solution

To solve this, we will use the properties of the normal distribution.

Given:

  • Mean μ=1.1kg\mu = 1.1 \, \text{kg}
  • Standard deviation σ=4.6kg\sigma = 4.6 \, \text{kg}

We are asked to find the probability that a randomly selected male college student gains between 0 kg and 3 kg during their freshman year. This is equivalent to finding the probability that XX (the weight gain) is between 0 and 3, i.e., P(0X3)P(0 \leq X \leq 3).

We can standardize this using the z-score formula:

z=xμσz = \frac{x - \mu}{\sigma}

Step 1: Find the z-scores for 0 kg and 3 kg.

  • For X=0kgX = 0 \, \text{kg}: z0=01.14.6=1.14.60.2391z_0 = \frac{0 - 1.1}{4.6} = \frac{-1.1}{4.6} \approx -0.2391

  • For X=3kgX = 3 \, \text{kg}: z3=31.14.6=1.94.60.4130z_3 = \frac{3 - 1.1}{4.6} = \frac{1.9}{4.6} \approx 0.4130

Step 2: Use the standard normal distribution table or a calculator to find the probabilities corresponding to these z-scores.

  • P(z0)0.4052P(z_0) \approx 0.4052 (probability corresponding to z0=0.2391z_0 = -0.2391)
  • P(z3)0.6604P(z_3) \approx 0.6604 (probability corresponding to z3=0.4130z_3 = 0.4130)

Step 3: Calculate the probability.

The probability that the student gains between 0 kg and 3 kg is:

P(0X3)=P(z3)P(z0)=0.66040.4052=0.2552P(0 \leq X \leq 3) = P(z_3) - P(z_0) = 0.6604 - 0.4052 = 0.2552

So, the probability is approximately 0.2552.


Would you like further clarification, or any details on this process?

Here are 5 additional questions based on this problem:

  1. How would the probability change if the standard deviation was larger?
  2. What is the probability that a student gains more than 3 kg during their freshman year?
  3. What z-score corresponds to a weight gain of 5 kg?
  4. If we randomly select 5 students, how would the probability of their average weight gain being between 0 and 3 kg change?
  5. How does the assumption of normal distribution affect the interpretation of this result?

Tip: The z-score standardizes values, allowing us to compare different normal distributions using the standard normal (mean 0, standard deviation 1).

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Probability
Statistics
Normal Distribution

Formulas

Z-score formula: z = (x - μ) / σ

Theorems

Standard Normal Distribution

Suitable Grade Level

College level (introductory statistics or probability courses)