exam 2 study ch 5-7 quiz answers
in which way do sample variances skew
positively
Probability allows us to make predictions regarding:
random events. random outcomes. random variables
The following samples were selected by two researchers. Which is associated with a smaller standard error of the mean?Researcher A: n = 18, μ = 8, σ = 2.4Researcher B: n = 12, μ = 8, σ = 2.4
researcher A
What is the implication for the tails of a normal distribution being asymptotic?
that extreme scores are possible in a normal distribution
Two outcomes are said to be mutually exclusive when
the probability of the two outcomes occurring together is equal to zero (p = 0)
A professor records the following final exam scores: 78 ± 7 (M ± SD). Students scoring in the top 14% get an A. What is the cutoff score for the top 14% in this example?
86.65
A researcher determines that students study an average of 80 ± 20 (M ± SD) min/week. Assuming these data are normally distributed, what is the z score for students studying 60 min/week?
-1.0
What is the z score for scores in the bottom 10%?
-1.28
Which of the following is a possible value for the standard deviation of a normal distribution?
.5
Which of the following ARE characteristics of probability
1. Probability varies between 0 and 1. 2. Probability can never be negative. 3. Probability can be stated as a fraction or decimal.
By definition, the probability of an outcome or event is
1. the proportion of times an outcome is likely to occur 2. the fraction of times an outcome is likely to occur. 3. particularly useful for predicting the likelihood of random events.
What is the z score for scores in the top 2.5%?
1.96
A gambler rolls a 3 with one roll of a single fair die. Given that the die was six-sided, what was the probability of rolling a 3 with one roll?
1/6
What is the central limit theorem?
It explains that a sampling distribution of possible sample means is approximately normally distributed, regardless of the shape of the distribution in the population.
The proportion or fraction of times an outcome is likely to occur is referred to as
Probability
The total number of possible outcomes for a random variable is referred to as
Sample space
What type of distribution does the binomial distribution approximate?
a normal distribution
Most behavior is believed to ______ a normal distribution.
approximate
central limit theorem
basically, if the the sample size is large enough, the data will be normally distributed
A researcher selects two samples of 25 participants each. In the first sample, the population mean was 32 and the variance was 8. In the second sample, the population mean was 4 and the variance was 8. Which sample will be associated with a larger standard error of the mean?
both samples will have the same value of standard error
A researcher increases the sample size, which will:
decrease the value of standard error
Which of the following is an appropriate step for the normal approximation of the binomial distribution?
find the proportion located within the real limits check for normality find the real limits
Which of the following is NOT a characteristic of probability?
is used to describing fixed events
The shape of the sampling distribution of the mean is approximately ______, whereas the shape of the sampling distribution of the variance is approximately ______.
normal, positively skewed
What values are distributed along the x-axis for a sampling distribution of the sample variance?
sample variances
the standard error is the standard deviation for what type of distribution?
sampling distribution
The ______ converts any normal distribution with any mean and any variance to a standard normal distribution with a mean of 0 and variance of 1.
standard normal transformation
The mean can take on any value and the standard deviation can take on any positive value. Therefore,
there are an infinite number of possible normal distributions
The sample variance is an unbiased estimator of the population variance
when dividing SS by df and when dividing SS by n − 1.
