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A town's January high temperatures average \(36^{\circ} \mathrm{F}\) with a standard deviation of \(10^{\circ},\) while in July the mean high temperature is \(74^{\circ}\) and the standard deviation is \(8^{\circ} .\) In which month is it more unusual to have a day with a high temperature of \(55^{\circ} ?\) Explain.

Short Answer

Expert verified
The temperature of 55°F is more unusual in July.

Step by step solution

01

Understand the Given Information

We are provided with the average high temperatures and standard deviation for January, which are 36°F and 10°F respectively. For July, the mean high temperature is 74°F with a standard deviation of 8°F. We need to find out in which month a temperature of 55°F is more unusual.
02

Calculate January Z-score

To determine how unusual a temperature of 55°F is for January, we calculate the Z-score. The formula for the Z-score is:\[ Z = \frac{X - \mu}{\sigma} \]where \(X = 55\), \(\mu = 36\), and \(\sigma = 10\). Substitute the values:\[ Z_{January} = \frac{55 - 36}{10} = \frac{19}{10} = 1.9 \]
03

Calculate July Z-score

Similarly, we calculate the Z-score for July with \(X = 55\), \(\mu = 74\), and \(\sigma = 8\). Use the formula:\[ Z = \frac{X - \mu}{\sigma} \]Substitute the values:\[ Z_{July} = \frac{55 - 74}{8} = \frac{-19}{8} = -2.375 \]
04

Compare Z-scores

The absolute value of the Z-score indicates how many standard deviations away the temperature is from the mean. We compare the absolute values:\[ |Z_{January}| = 1.9 \]\[ |Z_{July}| = 2.375 \]Since \(|Z_{July}| > |Z_{January}|\), 55°F is more unusual in July than in January.

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Key Concepts

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

Z-score
A Z-score is a statistical measurement that describes how far away a data point is from the mean of a data set, expressed in terms of standard deviations. It helps understand how unusual or typical a specific observation is within a distribution. The formula for calculating the Z-score is:- Dissecting this formula, you'll see: - **X** is the value you are investigating, - **\( \mu \)** is the mean or average of the data set, and - **\( \sigma \)** is the standard deviation. - A positive Z-score indicates that the data point is above the mean, while a negative Z-score shows it's below the mean. If the Z-score is 0, that means it is exactly at the mean. - Calculating Z-scores can be useful for identifying outliers, which are data points that are significantly different from others in the data set. In our temperature situation, calculating the Z-score for January and July allows us to determine which month a temperature of 55°F is more unusual.
Mean Temperature
The mean temperature, commonly known as the average temperature, is a central value that represents a data set. It's calculated by summing up all temperature values and then dividing by the number of values. - For instance, the mean temperature for January in our problem is given as 36°F, and for July, it is 74°F. These mean values give a central idea of what the typical high temperatures might be in each month. - Knowing the mean helps us have a reference point when comparing specific temperatures to see if they fall within a normal range for the month, or if they are likely to be considered unusual. - In statistical terms, understanding the mean helps in setting a baseline for expecting climate behavior. Fluctuations such as the 55°F measurement can then be evaluated more effectively using something like the Z-score, which shows the deviation from this mean.
Statistical Analysis
Statistical analysis is a crucial tool in understanding data, especially when you're dealing with natural phenomena like temperature changes. It encompasses a variety of methods for collecting, reviewing, and drawing conclusions from data. Techniques like the calculation of Z-scores, means, and standard deviations are foundational in statistical analysis. - A comprehensive statistical analysis involves: - **Collecting Data**: Getting a set of data, such as the temperatures for January and July. - **Describing Data**: Summarizing features through metrics like mean and standard deviation. - **Interpreting Data**: Using tools like Z-scores to understand variability and identify how an unusual measurement like 55°F fits within the data. - Conducting a statistical analysis helps uncover patterns or irregularities in datasets. In this temperature scenario, statistical analysis allows us to quantify how unusual 55°F is relative to the norm for each month by converting temperatures into Z-scores. This quantitative approach enables informed decision-making or hypothesis testing in various fields, including meteorology.

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