X, x̄, or p̂?
This statistic represents the average GPA of 50 randomly selected students.
What is x̄?
Find the standard error of a sample mean.
What is σ/√n?
Which calculator command finds a probability?
What is normalcdf?
For sample means, the CLT generally applies when n is at least this value.
What is 30?
A population has μ=100, σ=20, and n=64. Find the standard error.
What is 20/√64 = 2.5?
This statistic represents the proportion of students in a sample who work while attending school.
What is p̂?
Find the standard error of a sample proportion.
What is √(p(1-p)/n?
Which calculator command finds a cutoff value?
What is invNorm?
A sample proportion problem requires checking these two values
What are np and n(1−p)?
A beverage company fills bottles with a mean of 20 ounces and standard deviation of 2 ounces. Random samples of 64 bottles are selected. Find the probability that the sample mean is between 19.5 and 20.25.
What is 0.8186
standard error = 2/√64 =0.25
normalcdf(19.5,20.25,20,0.25) = 0.8186
A randomly selected student's exam score.
What is X?
The mean of the sampling distribution of x̄.
What is μx̄=μ?
"Find the probability that a student studies more than 15 hours."
Which command should be used?
What is normalcdf?
For a proportion problem, np=8. Can we use the normal approximation?
What is No?
A college reports that 60% of students work while attending school. A sample of 100 students is selected. Find the probability that more than 65% work.
What is 0.1537?
σp̂ = √(0.60)(1-0.60)/100 =0.0031 0.0490
normalcdf(0.65,9999,0.60,0.0490) = 0.1537
The average battery life of a sample of 25 batteries
What is x̄?
The mean of the sampling distribution of p̂.
What is μp̂=p?
"Find the sample mean that marks the top 10%."
Which command should be used?
What is invNorm?
For a proportion problem, np=30 and n(1−p)=25. Can we use the normal approximation?
What is Yes?
A retailer reports that 42% of customers use digital coupons. A random sample of 225 customers is selected. What sample proportion marks the lowest 10% of all possible sample proportions?
What is 0.3778?
σp̂ = √(0.42)(1-0.42)/225 =0.0329
invNorm(0.10,0.42,0.0329) = 0.3778
The percentage of sampled students who use tutoring services.
What is p̂?
For sample means, increasing the sample size causes this quantity to decrease.
What is the standard error?
What area should be entered into invNorm when finding the top 5%?
What is 0.95?
Why do we check CLT conditions? What are we checking?
To determine whether the sampling distribution is approximately normal.
A university reports that 68% of students have attended at least one campus event this semester. A random sample of 196 students is selected. What sample proportion marks the lowest 2.5% of all possible sample proportions?
What is 0.6147?
σp̂ = √(0.68)(1-0.68)/196 = 0.03332
invNorm(0.025,0.68,0.03332) = 0.6147