Proportion Refreshers
CI for Means
Test for Means
Spring Trivia
100
You want to estimate the proportion of your classmates that send more than 50 texts a day. Should you run a test or find a confidence interval to answer this question?
To estimate a number, find a confidence interval.
100
For what variables do we use the t-distribution: Means or Proportions?
Means
100
The part of your hypothesis that always has an equal sign
Null
100
Is this true or false? Tornadoes are more prevalent in the spring.
True
200
How do you check the large enough condition for inference with proportions?
Check np and nq. If the null hypothesis proportion would predict 10 successes and 10 failures with the given sample size then it is large enough.
200
People applying for a driver's license In California usually need to take a multiple choice test as a part of the application process. An administrator of these tests is curious about how much time people spend on the test. They take an SRS (simple random sample) of 15 test results and find that the times are strongly skewed to the left with a mean of x=14.2 minutes. There are also a few outliers in the sample data. Which conditions for constructing a t interval have been met?
Random/Independent
200
The normal condition when n isn't greater than or equal to 30 or from a normal population
Graph: no obvious skew or outliers
200
According to legend, if a groundhog does not see his shadow when he emerges from his hole on Groundhog Day, Spring will arrive (late or early)
Early
300
Calculate the standard deviation of p hat if:
p = 0.34
n = 400
.0237
300
Camila is curious about the average length of the female blue whales her organization monitors. She takes a random sample of 4 female blue whales from this population. Their average recorded length is x=78 and their standard deviation is sx=10. The distribution of lengths in the sample is roughly symmetric with no obvious outliers.
Based on this sample, create a 95% confidence interval for the mean length (in meters) of female blue whales
(62.09,93.91)
300
Pepsi claims that Bubly has 12.0 oz in each can and you suspect that number is too high. You take a random sample of 65 Bubly cans, and measure the amount of water in each can. You find that the average of the cans in your sample is 11.95 oz with a deviation of .2 ounces. Find the p-value for this question.
p = .024
300
In the Southern Hemisphere, which month marks the start of spring?
September
400
In a representative sample of 100 people, 53% approve of the president. Find a 95% confidence interval to report the data.
A 1-prop z-int with x=53 n=100 and CL = .95 gives a confidence interval between 43% and 63% approval.
400
A random sample of 22 people resulted in a 87% confidence interval of (5.8, 12.2). What was the sample mean and margin of error?
PE = 9
MOE = 3.2
400
The average height of 18-year-old American women is 64.2 inches. You wonder whether the mean height of this year’s female graduates from a large local high school differs from the national average. You measure an SRS of 48 female graduates and find that x¯=63.5 inches and sx=3.7 inches . Make an appropriate conclusion
ts = -1.31, p-value = .196, there is not enough evidence to suggest this class is different than the population.
400
March is named after which Roman God?
Mars (Aries), the Roman God of war
500
What is the margin of error for the confidence interval (0.55, 0.72)
.085
500
Which of the following would make the margin of error decrease?
a) Increasing sample size
b) Decreasing sample size
c) Increasing Confidence Level
d) Decreasing Confidence Level
e) Decrease sample mean
f) Decrease sample sd
a, d, f
500
What does a p-value of 3% really mean in a test of significance?
P-value is the chances of the event occuring in the null hypothesis model. If we choose to reject the null hypothesis, there's a 3% chance of making a mistake.
500
Which ancient building in Africa was constructed facing the direction where the sun rises on the first day of spring?
Great Sphinx
