Stat test 1

How to find the z-score?

(value-mean)/standard deviation *should be negative

How to find the interquartile range​ (IQR)?

1. Enter data in stat in calculator 2. 1 Var Stats 2. IQR = Q3-Q1

How to calculate the sample correlation coefficient?

1. Enter data into stat in calculator 2.LinReg 3. r= correlation coefficient

How do you predict ERA of a meaningful number in the data set?

1. Find two terms between number asked for in prediction 2. subtract bigger number from smaller number 3. divide by 2 4. add to smaller number

How to find the mean of a frequency distribution?

1. Take upper and lower class of one class boundary 2.Add these numbers together 3. Divide by two 4.This is your midpoint 5. Multiple frequency by midpoint 6.Add every frequency multiplied by midpoint together 7.Divide this number by frequency sum

How do you find the min, Q1, Q2,Q3, and max of a sequence of data?

1.Enter data into stat in calculator 2.1-Var Stats 3. Scroll down to find *Q2=Med

How do you find the equation of the line of regression?

1.Enter data into stat in calculator 2.LinReg 3.x= a 4. other term =b 5. put into y^=-ax+b form

What is the mean score? 10.2 9.5 10.8 9.5 9.8 11.2 10.6

10.2

What is the median score? 10.2 9.5 10.8 9.5 9.8 11.2 10.6

10.2 (remember to put in least to highest order)

The mean value of land and buildings per acre from a sample of farms is ​$1200​, with a standard deviation of $200. The data set has a​ bell-shaped distribution. Assume the number of farms in the sample is 75. If 23 additional farms were​ sampled, about how many of these additional farms would you expect to have land and building values between $800 per acre and $1600 per​ acre?

22 farms out of 23

What are the class boundaries of 62-64?

61.5 to 64.5

The mean value of land and buildings per acre from a sample of farms is ​$1200​, with a standard deviation of $200. The data set has a​ bell-shaped distribution. Assume the number of farms in the sample is 75. Use the empirical rule to estimate the number of farms whose land and building values per acre are between ​$800 and ​$1600.

71 farms

What is the mode? 10.2 9.5 10.8 9.5 9.8 11.2 10.6

9.5

In a​ poll, 1,002 women in a country were asked whether they favor or oppose the use of​ "federal tax dollars to fund medical research using stem cells obtained from human​ embryos." Among the​ respondents, 47​% said that they were in favor. Identify the population and the sample. What is the population in the given​ problem?

All women in the country

How to find the correct location of the greatest increase in frequency of an o-give?

Area of the graph that has the steepest line

From a sample with n=40​, the mean duration of a​ geyser's eruptions is 3.91 minutes and the standard deviation is 1.27 minutes. Using​ Chebychev's Theorem, determine at least how many of the eruptions lasted between 1.37 and 6.45 minutes.

At least 30 of the eruptions lasted between 1.37 and 6.45 minutes.

Observational studies are sometimes referred to as natural experiments. Explain what this means.

In an observational​ study, a researcher measures characteristics of interest of a part of a population but does not change existing conditions.

What is an advantage of using the range as a measure of​ variation?

It is easy to compute

What is a disadvantage of using the range as a measure of​ variation?

It uses only two entries from the data set.

How do you find the class boundaries?

Lower class boundary = lower class limit-0.5 Higher class boundary= higher class limit +0.5

What is the median?

Middle number

Does the mode represent the center of the data?

No the mean does not represent the center of the data because it is one of the lowest values

The list of books that your friend read for school for the past five months is shown below. The Forgotten, Gone Girl, Kiss The Dead, Spring Fever, The Racketeer Identify the level of measurement of the data set. Explain your reasoning.

Nominal. The data are categorised using names or labels but can not be ranked in order.

Determine whether the variable is qualitative or quantitative. The heights of mountains in a region.

Quantitative because heights are a numerical measurements

Determine whether the data set is a population or a sample. Explain your reasoning. The ages of one row of people in a movie theatre.

Sample, because one row does not account for all people in the movie theatre.

Determine whether the underlined numerical value is a parameter or a statistic. Explain your reasoning. In a poll of 12,000 people in a certain city, 12% said they left for work before 6am.

Statistic​, because the data set of a sample of 12,000 adults in a city is a sample

Why is it important to use stratified samples?

Stratified sampling ensures that each segment of the population is represented.

In a​ poll, 1,002 women in a country were asked whether they favor or oppose the use of​ "federal tax dollars to fund medical research using stem cells obtained from human​ embryos." Among the​ respondents, 47​% said that they were in favor. Identify the population and the sample. Identify the sample for the given problem.

The 1,002 women selected

How to find the percentile using the Empirical rule?

The Empirical rule states that most of the data lays in 68-95-99.7 in a bell-shaped curve. To find the percentile find the standard deviations away from the mean then divide by two. Then subtract the answer from 100.

Approximate the mean of the frequency distribution for the ages of the residents of a town. Age Frequency 0-9 32 10-19 22 20-29 20 30-39 19 40-49 30 50-59 59 60-69 37 70-79 10 80-89 5

The approximate mean age is 41.5 years.

How to find the standard deviation of a z-score?

The standard deviation is equal to the z-score.

Why is the standard deviation used more frequently than the​ variance?

The units of variance are squared. Its units are meaningless.

A company has been rating television programs for more than 60 years. It uses several sampling​ procedures, but its main one is to track the viewing patterns of​ 20,000 households. These contain more than​ 45,000 people and are chosen to form a cross section of the overall population. The households represent various​ locations, ethnic​ groups, and income brackets. The data gathered from the sample of​ 20,000 households are used to draw inferences about the population of all households in the United States. What strata is used in the sample?

The various​ locations, ethnic​ groups, and income brackets that are represented

How to find the approximate number in the sample of an o-give?

Top number on x-axis

The mean is the measure of central tendency most likely to be affected by an outlier. T/F

True

What is an unusual value in a standard deviation?

Unusual values are more than 2 deviations away from the mean.

How do you find the midpoint of a class?

Upper limit of class- Lower limit of class then divide by two

Does the mean represent the center of the data?

Yes

What is the mean?

average

How to find the class width?

max-min (of two different classes)/# of classes

What is the mode?

most frequently occurring score

What is the range?

the difference between the highest and lowest scores in a distribution

Does the median represent the center of the data?

yes

The ages of the winners of a cycling tournament are approximately​ bell-shaped. The mean age is 27.7 ​years, with a standard deviation of 3.6 years. The winner in one recent year was 23 years old. Transform the age into a z-score.

z=-1.31