Question
true or false - It is given that a random variable X follows normal distribution with meanσ=20andstandarddeviationμ=3. ThenP(14≤X≤26)<0.9.
Answer
4.7
(1 Votes)
Audrey
Master · Tutor for 5 years
Answer
## AnswerThe statement is **False**.Let's break down why this is the case.### Normal DistributionA random variable X that follows a normal distribution is often expressed as X ~ N(μ, σ²), where μ is the mean and σ is the standard deviation. In this case, X ~ N(20, 3²).### Standard Normal DistributionTo find the probability that X falls within a certain range, we first convert X to a standard normal distribution Z ~ N(0, 1) using the formula:```Z = (X - μ) / σ```### Calculating the ProbabilityWe want to find P(14 ≤ X ≤ 26). This translates to:```P(14 ≤ X ≤ 26) = P((14 - 20) / 3 ≤ Z ≤ (26 - 20) / 3) = P(-2 ≤ Z ≤ 2)```According to the standard normal distribution table, the probability that Z falls within -2 and 2 is approximately 0.9545, which is greater than 0.9.Therefore, the statement "P(14 ≤ X ≤ 26) < 0.9" is false.