Home › AP Statistics › Statistics › Discrete Random Variables › In the notation used for a discrete random varia…
In the notation used for a discrete random variable, what does a lower case letter such as x represent?
AOne specific numerical value the variable takes
BThe random variable's name, spoken in words
CThe probability attached to an outcome
DThe total count of trials performed
Answer & Solution
Correct answer: A. One specific numerical value the variable takes
1. Convention reserves upper case X for the random variable itself, written and read in words.
2. Lower case x is used for one particular numerical value that X can take on.
3. Option B describes upper case X, not lower case x, so it is the wrong role.
4. Options C and D describe a probability and a trial count, neither of which is what x denotes.
_Source: OpenStax Introductory Statistics (CC BY 4.0), Ch 4 "Discrete Random Variables", section 4.1 Probability Distribution Function (PDF) for a Discrete Random Variable_
Related questions
Mrs. Plum's cats wake her up an average of ten times per week, so X ~ P(10). What is P(x≤5The average number of children a Spanish woman has in her lifetime is 1.47, so X ~ P(1.47)Pierre, an amateur chef, drops an average of 1.5 pieces of egg shell into each cake he bakContinuing the IRS audit example with X ~ P(2), what is P(x≥3), the probability that at leThe chance of an IRS audit for a return over $25,000 is about 2% per year. For 100 such taA manufacturer finds 3% of its Christmas light bulbs defective. For a string of 100 lightsFor 200 days with a 1.02% chance of low seismic activity per day in Alaska, the binomial mText message users send or receive an average of 41.5 texts per day. Converted to an hourl