Question

Approximate the mean of the frequency distribution for thepopulations (in thousands) of the counties in a certain state. Population ( in thousands ) Frequency 0 - 19 42 20 - 39 1 40 - 59 2 60 - 79 2 80 - 99 2 100 - 119 4 120 - 139 0 140 - 159 2

Answer 1

To approximate the mean of a frequency distribution, use the midpoint of class intervals multiplied by their frequency, then divide by the total frequency. Probabilities cannot be determined without full data. For the U.S. Census study, X is 8.2 minutes, σ is 2.2 minutes, and n is 200 people.

Step-by-step explanation:

To calculate the mean of the frequency distribution for the populations of counties, we use the midpoint of each class interval times its frequency. Summing these products and dividing by the total number of counties gives us the approximate mean of the distribution.Considering the information provided, we do not have enough context to determine if 1,956.8 refers to a population or a sample mean. Hence, this part of the question can not be accurately addressed.To find the probability of a selected district having fewer than 1,600 votes, or between 1,800 and 2,000 votes, we need a complete distribution of votes. Without this, we cannot determine these probabilities or the third quartile for votes for the candidate.For the U.S. Census Bureau study, the mean time (X) needed to complete the short form is 8.2 minutes, the standard deviation (σ) is 2.2 minutes, and the sample size (n) is 200 people.