Sampling Distribution Basics
A smaller group taken from a population to collect data.
What is sample?
What letter is the mean when sampling proportion?
What is p?
When do we use the sample mean distribution formula ?
If the sample size is less than 30
What sample size is typically considered large enough for the CLT to apply?
30 or more
Why do we use samples instead of entire population?
It saves time money and effort?
what two conditions must be met to determine if the proportion is normal ?
What is np≥10 and n( 1 − p)≥10?
What does the standard deviation tells us ?
How far the numbers are from the mean?
What does “σ “ mean?
What is standard deviation?
When you are looking for “at least” that is your upper bound.
What is False?
What is the standard deviation of p^, for population proportion, p= 0.4 and you take a random sample of size 100?
What is 0.049 ?
What does xˉ mean?
The population mean?
A student was solving for standard deviation and divided the standard deviation by n. What is the mistake ?
It should be divided by the sqrt(n)
Increasing sample size decreases the variability.
what is true?
In a random sample of 100 people, 60% say they like pineapple on pizza. Assuming the population proportion is 0.6, what is the standard deviation of the sampling distribution of p^?
What is 0.049?
A group has a mean of 50 and a standard deviation of 10. What is the standard deviation of the sample mean for samples of size 25?
10
A population has a mean of 75 and a standard deviation of 20. What is the probability that a sample of size 36 has a mean greater than 80?
σxˉ = 20/square root of 36 = 3.33
z = (80-75)/3.33 ≈ 1.5
P(xˉ>80) = P(Z>1.5) ≈ 0.0668
Why do we have to randomize the sample?
To avoid bias
A survey shows 45% of students like block schedules. A sample of 200 students is taken. What is the probability the sample proportion is between 50% and 60%
What is =0.077?
In a quality check, a sample of 25 batteries has an average charge of 98 hours and a standard deviation is 8. What's the probability of the batteries lasting less than 98 hours?
What is 0.50?
For a population with mean 100 and standard deviation 20, what would be the approximate shape of the sampling distribution of the mean for n=40?
Approximately normal. (40≥30, CLT suggests approximately normal)