Random Variable
A random variable that can take countable values is called ______.
continuous
The sum of all probabilities in a probability distribution is equal to _____.
1
The expected value of a random variable is also known as the _____.
Mean
Which symbol is used for the mean of a random variable?
μ
A normal distribution curve is ______.
Symmetric
The set of all possible values of a random variable is called its ______.
Range
The highest point of the normal curve represents the ______.
Mean
The standard normal table gives the ______ under the curve.
Area
A small variance indicates that the values are ______.
close to the mean
The number of customers entering a store per hour is a ______ random variable.
Discrete
Which graph is commonly used to illustrate a probability distribution?
Histogram
What happens to the z-score if the value is above the mean?
Positive
Which best explains the difference between discrete and continuous random variables?
Discrete is counted; continuous is measured
Z-scores are used to ______.
A. find variance B. locate values on the normal curve C. count frequencies D. draw graphs
locate values on the normal curve
The standard deviation of a standard normal distribution is _____.
1
Why is the normal distribution important in statistics?
A. It only applies to games B. It models many real-life situations
C. It replaces probability D. It avoids computation
B. It models many real-life situations
Percentiles show the ______ of a value in a distribution.
A. position B. frequency C. variance D. mean
Frequency
Why must probabilities in a distribution add up to 1?
A. To find variance B. To represent all possible outcomes
C. To compute z-score D. To draw the curve
To represent all possible outcomes
A random variable X has a mean of 6 and a standard deviation of 2. Find the corresponding z-score for x = 11.
2.5
Who discovered the Bell- Shaped Curve of a normal curve.
Carl Friedrich Gauss
What does the mean of a probability distribution represent?
A. Most frequent value B. Expected outcome C. Spread of data D. Highest probability
Highest probability
Which region under the normal curve represents most of the data?
A. Far tails B. Center C. Right tail D. Left tail
Center
The scores in the summative test of 11- TVL B are normally distributed with a mean of 65 and a standard deviation of 12. Find the probability that some students got a score below 40.
P(Z<−2.08)≈0.0188 1.88%
What is the area under the curve for z= -1.43
0.0764
Give atleast 4 characteristics of a normla curve.
1.The distribution curve is bell- shaped.
2.The curve is symmetrical about its mean.
3.The mean, median and mode coincide at the center.
4.The curve is asymptotic to the base line.
5. Classified by two parameters: Mean-represent location and standard deviation represent spread.
6. The width of the curve is determined by the standard deviation of the distribution.
7. The area under the curve is 1.