Math Problem Statement

The following data represent the​ high-temperature distribution for a summer month in a city for some of the last 130 years. Treat the data as a population. Complete parts​ (a) through​ (c). Temperature ​50-59 ​60-69 ​70-79 ​80-89 ​90-99 ​100-109

Days 4 303 1434 1527 475 7 Question content area bottom Part 1 ​(a) Approximate the mean and standard deviation for temperature. muequals

80.8 ​(Round to one decimal place as​ needed.) Part 2 sigmaequals

enter your response here ​(Round to one decimal place as​ needed.)

Solution

To approximate the mean and standard deviation for the given temperature distribution, we can treat the data as a grouped frequency distribution. Let's calculate these values step by step.

Given Data:

  • Temperature intervals: 505950-59, 606960-69, 707970-79, 808980-89, 909990-99, 100109100-109
  • Corresponding days: 44, 303303, 14341434, 15271527, 475475, 77

Step 1: Determine the midpoints of each interval

The midpoint (xix_i) of each interval is calculated as follows: Midpoint=Lower limit+Upper limit2\text{Midpoint} = \frac{\text{Lower limit} + \text{Upper limit}}{2}

  • Midpoint for 505950-59 = 50+592=54.5\frac{50 + 59}{2} = 54.5
  • Midpoint for 606960-69 = 60+692=64.5\frac{60 + 69}{2} = 64.5
  • Midpoint for 707970-79 = 70+792=74.5\frac{70 + 79}{2} = 74.5
  • Midpoint for 808980-89 = 80+892=84.5\frac{80 + 89}{2} = 84.5
  • Midpoint for 909990-99 = 90+992=94.5\frac{90 + 99}{2} = 94.5
  • Midpoint for 100109100-109 = 100+1092=104.5\frac{100 + 109}{2} = 104.5

Step 2: Calculate the mean (μ\mu)

The mean is calculated using the formula: μ=(fixi)fi\mu = \frac{\sum (f_i \cdot x_i)}{\sum f_i} Where:

  • fif_i is the frequency (days)
  • xix_i is the midpoint of the interval

Let's compute this step by step.

Step 3: Calculate the squared deviations and standard deviation (σ\sigma)

The standard deviation is calculated using: σ=(fi(xiμ)2)fi\sigma = \sqrt{\frac{\sum (f_i \cdot (x_i - \mu)^2)}{\sum f_i}}

I'll calculate the standard deviation now.The standard deviation (σ\sigma) of the temperature distribution is approximately 8.28.2 (rounded to one decimal place).

Summary:

  • Mean (μ\mu): 80.8
  • Standard Deviation (σ\sigma): 8.2

Would you like more details, or do you have any questions?

Here are some related questions:

  1. How do you interpret the mean and standard deviation in this context?
  2. What is the significance of treating the data as a population rather than a sample?
  3. How would the calculation change if this were considered a sample instead of a population?
  4. What could be inferred if the standard deviation were significantly higher or lower?
  5. How might the distribution of temperatures change over a different time span?

Tip: Understanding how the mean and standard deviation relate to the data's distribution can provide insights into the data's spread and central tendency.

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Math Problem Analysis

Mathematical Concepts

Statistics
Mean
Standard Deviation
Grouped Frequency Distribution

Formulas

Mean formula
Standard deviation formula

Theorems

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Suitable Grade Level

High School