BUAL 2650 EXAM 1 QUESTIONS & ANSWERS
What is quantitative value that represents the outcomes from an experiment? - Answer
-Random Variable
What are the 2 kinds of random variables? - Answer -discrete (countable) and
continuous (decimals)
What is the most common type of continuous probability distribution? - Answer -normal
distribution
What are some other names for a continuous probability distribution? - Answer -
probability curve and probability density function (pdf)
What is the total area under the curve if f(x) always equal to? - Answer -1 or 100%
What is an area under a continuous probability distribution? - Answer -a probability
How many types of normal curves are there? - Answer -an infinite amount
What does the shape of any individual normal curve depend on? - Answer -its specific
mean and standard deviation (also median and mode)
What is the highest point over? - Answer -the mean, median, mode
Is the normal curve symmetric? - Answer -yes (left and right are mirror images)
What does a larger standard deviation do to a curve? - Answer -makes it shorter and
wider
Do the tails of a normal curve ever touch the horizontal axis? - Answer -no
What percent of the area under the normal curve is within 1 standard deviation to the
left and right? - Answer -68.26
What percent of the area under the normal curve is within 2 standard deviation to the
left and right? - Answer -95.44
What percent of the area under the normal curve is within 3 standard deviation to the
left and right? - Answer -99.73
How do you calculate a z-score? - Answer -(value-mean)/standard deviation
What is the difference between x and z? - Answer -x is normal distribution where z is
standard normal distribution
, What is cumulative probability? - Answer -means less than, the left side under curve
What must you do to find probability to the right of a Z score? - Answer -1 - value from
Z table
P (z< 2) - Answer -0.9772
P (z<1.25) - Answer -0.8944
P (z>2.3) - Answer -0.0107
P (-1 < z< 2) - Answer -0.8185
Suppose x is a normally distributed variable from N(300, 15). P(x>280) - Answer -
0.9082
Find Z0.025 - Answer -1.96
What is xbar? - Answer -the sample mean
What is n? - Answer -sample size
What is N? - Answer -population size
Is calculating population mean easy to do? - Answer -usually no, which is why we take
samples
Why do we take samples? - Answer -the value of bar is used to make inferences about
the value of u.
What is a statical inference? - Answer -Point Estimation
What is the point estimation sample mean? - Answer -xbar
What is the point estimation for sample standard deviation? - Answer -S
What is the point estimation for sample proportion? - Answer -p-hat
Mxbar = ? - Answer -M
Standard deviation of the sample = ? - Answer -standard deviation / square root of n
How large does a sample size have to be in order to be considered normal? - Answer -
30
What is quantitative value that represents the outcomes from an experiment? - Answer
-Random Variable
What are the 2 kinds of random variables? - Answer -discrete (countable) and
continuous (decimals)
What is the most common type of continuous probability distribution? - Answer -normal
distribution
What are some other names for a continuous probability distribution? - Answer -
probability curve and probability density function (pdf)
What is the total area under the curve if f(x) always equal to? - Answer -1 or 100%
What is an area under a continuous probability distribution? - Answer -a probability
How many types of normal curves are there? - Answer -an infinite amount
What does the shape of any individual normal curve depend on? - Answer -its specific
mean and standard deviation (also median and mode)
What is the highest point over? - Answer -the mean, median, mode
Is the normal curve symmetric? - Answer -yes (left and right are mirror images)
What does a larger standard deviation do to a curve? - Answer -makes it shorter and
wider
Do the tails of a normal curve ever touch the horizontal axis? - Answer -no
What percent of the area under the normal curve is within 1 standard deviation to the
left and right? - Answer -68.26
What percent of the area under the normal curve is within 2 standard deviation to the
left and right? - Answer -95.44
What percent of the area under the normal curve is within 3 standard deviation to the
left and right? - Answer -99.73
How do you calculate a z-score? - Answer -(value-mean)/standard deviation
What is the difference between x and z? - Answer -x is normal distribution where z is
standard normal distribution
, What is cumulative probability? - Answer -means less than, the left side under curve
What must you do to find probability to the right of a Z score? - Answer -1 - value from
Z table
P (z< 2) - Answer -0.9772
P (z<1.25) - Answer -0.8944
P (z>2.3) - Answer -0.0107
P (-1 < z< 2) - Answer -0.8185
Suppose x is a normally distributed variable from N(300, 15). P(x>280) - Answer -
0.9082
Find Z0.025 - Answer -1.96
What is xbar? - Answer -the sample mean
What is n? - Answer -sample size
What is N? - Answer -population size
Is calculating population mean easy to do? - Answer -usually no, which is why we take
samples
Why do we take samples? - Answer -the value of bar is used to make inferences about
the value of u.
What is a statical inference? - Answer -Point Estimation
What is the point estimation sample mean? - Answer -xbar
What is the point estimation for sample standard deviation? - Answer -S
What is the point estimation for sample proportion? - Answer -p-hat
Mxbar = ? - Answer -M
Standard deviation of the sample = ? - Answer -standard deviation / square root of n
How large does a sample size have to be in order to be considered normal? - Answer -
30
