Question

A study was conducted to determine what percentage of people wash their hands when flying. Around 30% of people using restrooms in New York airports, 19% of those in Miami's airport, and 27% in Chicago are not bothering to wash their hands, while 96% of travelers passing through the Toronto International Airport did wash their hands. Overall, 78% of travelers washed their hands in airport bathrooms, according to the survey, which was conducted by Wirthlin Worldwide. The observers would pretend to be passengers using the restroom and noted the hand washing habits of 7,500 people as they passed through airports bathrooms in six major cities.

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1. What type of sampling was used to collect flyers hand washing habits?

		Simple Random Sample
		Stratified Sampling
		Multistage Sampling
		Systematic Sampling
		Cluster Sampling

2.

The statement “96% of passengers in Toronto International Airport washed their hands” is an example of why type of probability?

		Random Probability
		Marginal Probability
		Joint Probability
		Conditional Probability

3. Do you think the percentages described are representative of how often flyers wash their hands in airports, or would these percentages over or underestimated the true proportion in those cities’ airport bathrooms? Briefly explain your answer.

Answer 1

1. Here the major cities can be considered as stratas. The samples i.e. the flyers are then selected from each strata.

So, the sampling technique is stratified sampling.

2. If the selected airport is Toronto International Airport, then 96% of the passengers washed their hands.

So, the probability in this case is conditional probability.

3. The sample size considered to obtain tbe percentage of passengers washing their hands is 7500. The sample size is lare enough to be a good representative of the population. Also, samples are taken from 6 major cities to avoid the selection biasness of restricting to a specific airport. So, the percentages described in this case are good representative of the population.