Chapter 1
The student is doing a school wide survey and records the following data from students: grade level and their score on the PSAT. Which of the variables are categorical and which are quantitative?
Categorical: Grade level
Quantitative: PSAT score
What does the empirical rule state?
Following a normal distribution, 68% of the data falls within 1 standard deviation of the mean, 95% falls within 2 standard deviations of the mean and 99.7% falls within 3 standard deviations of the mean.
A student is performing an experiment on whether or not the type of soil used affects plant growth. What is the explanatory and response variable in this situation?
Explanatory Variable: Type of soil
Response Variable: Plant growth
What is simple random sampling?
Simple random sampling is a method used where each individual in a population has equal chance of being selected for a sample.
When you are tossing a coin, is the event of getting a head or a tail mutually exclusive or not?
This event is mutually exclusive because you can not toss a coin and land on both heads and tails at the same time.
Which is likely greater? The mean or median?
Mean is greater than median
How do you find the z-score of a group of data?
Z=x-mean/standard deviation
Amy has a predicted 100 meter dash time of 14 seconds. Her actual time is 14.5 seconds. What is the residual?
Residual=Actual Value-Predicted Value
Residual=0.5
What disadvantage might convenience sample provide?
Because convenience sampling is only done by people who choose to, this could result in bias and a lack of variety in the responses which generalizing the results to the population as a whole might not be accurate.
The probability of having a truck is 0.22, the probability of having an SUV is 0.54 and the probability of having a convertible is 0.11. What is the probability of having a sedan?
The probability is 0.13 because all probabilities in a distribution add up to 1 so 0.22+0.54+0.11=0.87 and 1-0.87=0.13.
An AP Statistics class votes on which food is their favorite out of sushi, pasta and pizza. The frequency on the y axis goes from 4 to 20. Sushi has a frequency of 5, pasta has a frequency of 17 and pasta has a frequency of 8. Why is this graph misleading?
The frequency scale on the y axis should start at 0, not 4.
What happens to the shape of data if you add or subtract a constant to each value?
The shape will stay the same.
What is the linear regression model.
The linear regression model is used to describe the relationship between a dependent variable and independent variable(s).
Why can't observational studies determine a causation?
Due to a possible confounding variable.
Do variances add or subtract when subtracting two independent random variables?
Variances add
A random sample of 1000 U.S. citizens were asked if they use Instagram. 550 minors responded and out of those 550, 437 of them use Instagram. 450 adults responded and out of that 450, 400 of them use Instagram. What proportion of the sample are adults?
450/1000=0.45
How do you find the IQR of a data set?
Order the data from smallest to largest, find the median to determine Q1 and Q3. Find the median for Q1 and Q3 and then subtract Q1 from Q3 to find the IQR.
Suppose that data was converted from centimeters to meters by diving the measurements by 100. How will this affect r^2 and s?
R^2 stays the same and s decreases
What is a randomized block design useful for?
It is useful for eliminating variability of data based on differences within the block.
If the number of trials are fixed, would the conditions be binomial or geometric?
The conditions would be binomial as number of trials is fixed.
Below is the SD and mean of sugar concentration in a Sprite can (in parts per million). Interpret the standard deviation. Mean: 0.147 SD: 0.340
The amount of sugar per Sprite can will typically vary by about 0.340 ppm from the mean of 0.147 ppm.
A class of 25 students are asked how many shoes they own. Anna reports owning 15 pairs of shoes and 19 out of the 25 students own less pairs than her. What percentile is Anna in the number of pairs of shoes distribution?
76th percentile
What would likely happen to the value of a correlation coefficient if an outlier was added to the data?
The correlation coefficient would decrease.
When is cluster random sampling effective?
When the clusters are similar to each other.
The standard deviation is 2.16 for amount of landlines in each household. If many, many household were selected at random, how would you interpret the value of 2.16.
The number of landlines would typically be about 2.16 from the mean.