Math Problem Statement

Assume that the readings at freezing on a batch of thermometers are normally distributed with a mean of 0°C and a standard deviation of 1.00°C. A single thermometer is randomly selected and tested. Find the probability of obtaining a reading between 0.907°C and 2.994°C.

Solution

To find the probability of obtaining a reading between 0.907°C and 2.994°C, we will use the properties of the normal distribution.

The readings follow a normal distribution with:

  • Mean (μ\mu) = 0°C
  • Standard deviation (σ\sigma) = 1°C

The probability of obtaining a reading between 0.907°C and 2.994°C is equivalent to finding the area under the normal curve between these two values.

Step 1: Convert the temperatures to z-scores.

The formula for the z-score is:

z=xμσz = \frac{x - \mu}{\sigma}

  • For x=0.907Cx = 0.907^\circ C:

z1=0.90701=0.907z_1 = \frac{0.907 - 0}{1} = 0.907

  • For x=2.994Cx = 2.994^\circ C:

z2=2.99401=2.994z_2 = \frac{2.994 - 0}{1} = 2.994

Step 2: Find the probabilities corresponding to these z-scores.

We can use a standard normal table or a calculator to find the probabilities for these z-scores.

  • The probability corresponding to z1=0.907z_1 = 0.907 is approximately 0.8176.
  • The probability corresponding to z2=2.994z_2 = 2.994 is approximately 0.9986.

Step 3: Calculate the probability between the two z-scores.

The probability of obtaining a reading between 0.907°C and 2.994°C is the difference between the two probabilities:

P(0.907<X<2.994)=P(z2)P(z1)=0.99860.8176=0.1810P(0.907 < X < 2.994) = P(z_2) - P(z_1) = 0.9986 - 0.8176 = 0.1810

Final Answer:

The probability of obtaining a reading between 0.907°C and 2.994°C is 0.1810 or 18.10%.

Would you like more details or have any questions?

Here are 5 related questions:

  1. How do you find probabilities for values below a certain z-score?
  2. What is the probability of obtaining a reading less than 0°C in this scenario?
  3. How do we calculate probabilities for non-standard normal distributions?
  4. How does changing the mean and standard deviation affect the probability?
  5. What is the probability of obtaining a reading above 3°C?

Tip: The total area under a normal distribution curve is always 1, representing a 100% probability for all possible outcomes.

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Math Problem Analysis

Mathematical Concepts

Statistics
Normal Distribution
Probability

Formulas

z-score formula: z = (x - μ) / σ
Probability between two z-scores

Theorems

Properties of the Normal Distribution
Empirical Rule

Suitable Grade Level

Grades 9-12