ANSWERS

  1. Identify the following numbers as parameters or statistics: A scientist is interested in whether a new light bulb lasts longer than the old brand. So he tests 100 old and 100 new bulbs. He finds that the old bulbs last on average 603.24 hours and the new bulbs last on average 713.76 hours.

603.24 – Statistic713.76 – Statistic

  1. Using the names below take an SRS of 5 people. Write down the names you select.

Instructions:

  1. Use TRD and read 2 digits at a time
  2. Let 01-20 each be a person; Ignore 21-99,00
  3. Read off 5 numbers and ignore repeats

01 Jim05 Matt09 Maria13 Amy17 Jason

02 John06 Pete10 Jenny14 Tom18 Justin

03 Suzy07 Dave11 Christine15 Chris19 Laura

04 Sarah08 Joe12 Megan16 Maureen20 Gretchen

81|95|9 5|99|51| 75|09|8 9|83|62| 18|78|3 1|75|94| 28|89|7 8|68|98| 87|76|5 9|88|20| 18|35|2 9|09|39| 71|86|8

2|87|85| 95|10|2 7|85|27| 02|020 05387 33879 29273 86115 43866 28811 06214 53559 44573

Chosen: 09-Maria, 18-Justin, 20-Gretchen, 10-Jenny, 02-John

  1. An economist is interested in the average price of gas in Philadelphia area. He drives around Philadelphia and records the price for Regular gas at the first 35 gas stations he sees. He finds that the average price for regular gas is $2.56 per gallon.
  2. What is $2.56?

Statistic

  1. What is the parameter of interest?

Average price for Regular gas in Philadelphia

  1. What is the sample?

The first 35 stations he comes across in Philadelphia

  1. What is the population?

All gas stations in Philadelphia

  1. What is the sample design?

Convenience Sample

  1. Would the results be reliable?

No random sampling was used so it could be biased. He looked in only one area of Philadelphia which could have different prices than the rest of the city.

  1. A Philadelphia talk show host is interested to hear reactions to the mayor’s proposal for a soda tax. He instructs his listeners to log onto the show’s website to voice their opinion. At the website the visitor is given this question: “Given that the city of Philadelphia collected over $418 million dollars in tax revenues last year, do you support or oppose a city-wide tax on sodas and sweetened drinks?” At the end of the day he finds that of 389 people that voted 321 were opposed to the new tax.
  2. What percent of people were opposed to the tax?

321/389 = 82.5%

  1. What is the parameter of interest?

Percent of all Philadelphians opposed to the soda tax

  1. What is the sample?

389 people that voted on the website

  1. What is the population?

All Philadelphians

  1. What is the sample design?

Voluntary Response Sample

  1. Would the results be reliable?

No. Since only those with strong opinions would likely take the time to go to the website and vote.

Also not all Philadelphians listen to the radio and the radio program to know about the vote.