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Reasoning Skills and Statistics Practice

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Updated on Sep 29, 2011

Review the lesson for Reasoning Skills and Statistics Help.

Reasoning Skills and Statistics Practice

Evaluate the following statistics. Are the sources credible? Why or why not?

  1. A survey conducted by the Heart and Home Baby Food Company shows that four out of five babies grow faster on formula than on breastmilk.
  2. According to the National Education Association (NEA), homeschooling does not provide a quality education for 80 percent of students.
  3. National Geographic recently announced that roughly 38 percent of the world's known species are near extinction.
  4. Read the following situation carefully and answer the question that follows.
    1. 5
    2. 50
    3. 500
    4. 1,000

Evaluate the following claims. Do the surveys seem to have representative samples, or could the samples be biased?

Do the following statistics compare apples and oranges, or are they fair comparisons?

  1. I bought this house in 1964 for just $28,000. Now it's worth $130,000. What a profit I've made!
  2. That shirt is $45. This one is only $15. They look exactly the same. I found a bargain!
  3. The total per capita income in Jewel County, adjusted for inflation, went up 12 percent in the last two years.

Answers

  1. This source is not credible because a baby food company has a personal interest in whether parents choose to formula feed or nurse their babies. Clearly, they will make more money if more parents choose formula.
  2. This source may seem credible because the topic is education and the NEA are experts in that area. However, homeschooling is a type of competition with public schooling, so the NEA may have a definite bias on the topic.
  3. The National Geographic is a reputable resource that has no vested interest in threatened species so this statistic can most likely be trusted.
  4. Five hundred responses (c) would probably be sufficient to give you a good idea of the overall sentiment on campus. If you could get 1,000 responses, however, your results would be much more accurate. Both 5 and 50 are far too small for sample sizes in this survey.
  5. The sample in this survey is clearly biased. If only women who have been victims of crimes on campus are surveyed, the results will certainly reflect a dissatisfaction with campus security. Furthermore, unless this is an all-female college, the sample is not representative.
  6. The sample in this survey is representative. People randomly stopped on the street in various parts of the city should result in a good mix of residents and visitors with all kinds of backgrounds and parking needs.
  7. This sample is not representative. Only a limited number of parents are able to find the time—or have the desire—to join the PTA. Parents who hold down two jobs, for example, aren't likely to be members, but their opinion about the extended school day is very important.
  8. The sample in this survey is representative. Parents who stop by the library represent a wide variety of incomes, backgrounds and lifestyles. They also have children in the right age group for playing or at least being familiar with video games.

Do the following statistics compare apples and oranges, or are they fair comparisons?

  1. I bought this house in 1964 for just $28,000. Now it's worth $130,000. What a profit I've made!
  2. That shirt is $45. This one is only $15. They look exactly the same. I found a bargain!
  3. The total per capita income in Jewel County, adjusted for inflation, went up 12 percent in the last two years.

 

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