The probability that the reaction time for this density function is at most 2.5 seconds is equal to 0.9.
<h3>What is a density function?</h3>
A density function can be defined as a type of function which is used to represent the density of a continuous random variable that lies within a specific range.
<h3>How to calculate the probability that reaction time is at most 2.5 seconds?</h3>
P(X ≤ 2.5) = Fx(2.5)
Fx(2.5) = 3/2 - 3/2(2.5)
Fx(2.5) = 3/2 - 3/5
Fx(2.5) = 0.9.
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Complete Question:
The reaction time (in seconds) to a certain stimulus is a continuous random variable with pdf:
f(x) = 
What is the probability that reaction time is at most 2.5 seconds?
I believe the answer is 17
Here are the 4 inequality signs.

---> a is less than b

---> a is less than or equal to b

---> a is greater than b

---> a is greater than or equal to b
For the second and fourth lines above, the two sides may or may not be equal.
For the first and third lines above, the two sides cannot be equal.
Answer:
68% of an investment earning a return between 6 percent and 24 percent.
Step-by-step explanation:
The Empirical Rule states that, for a normally distributed random variable:
68% of the measures are within 1 standard deviation of the mean.
95% of the measures are within 2 standard deviation of the mean.
99.7% of the measures are within 3 standard deviations of the mean.
In this problem, we have that:
Mean = 15
Standard deviation = 9
How likely is it to earn a return between 6 percent and 24 percent?
6 = 15 - 1*9
6 is one standard deviation below the mean
24 = 15 + 1*9
24 is one standard deviation above the mean
By the empirical rule, there is a 68% of an investment earning a return between 6 percent and 24 percent.