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A project is graded on a scale of 1 to 5. If the random variable, X, is the project grade, what is the mean of the probability distribution below? A probability distribution is shown. The probability of 1 is 0. 1; 2 is 0. 2; 3 is 0. 4; 4 is 0. 2; 5 is 0. 1. 0. 2 0. 4 1 2003.

Sagot :

Probability of an event is the measure of its chance of occurrence. The mean of the given probability distribution is 3

How to calculate the expectation(also called mean) of a discrete random variable?

Expectation can be taken as a weighted mean, weights being the probability of occurrence of that specific observation.

Thus, if the random variable is X, and its probability mass function is given as:  f(x) = P(X = x), then we have:

[tex]E(X) = \sum_{i=1}^n( f(x_i) \times x_i)[/tex]

(n is number of values X takes)

For the given case, we have:

X = project grade (from 1 to 5, thus, 1, 2,3,4, or 5 as its values.)

The probability distribution of X is given as:

[tex]\begin{array}{cc}x&P(X = X)\\1&0.1\\2&0.2\\3&0.4\\4&0.2\\5&0.1\end{array}[/tex]

Using the aforesaid definition, we get the mean of random variable X as:

[tex]E(X) = \sum_{i=1}^n( f(x_i) \times x_i)\\\\E(X) = 1 \times 0.1 + 2 \times 0.2 + 3 \times 0.4 + 4 \times 0.2 + 5 \times 0.1\\E(X) = 0.1 + 0.4 + 1.2 + 0.8+0.5 = 3[/tex]

Thus, the mean of the given probability distribution is 3


Learn more about expectation of a random variable here:

https://brainly.com/question/4515179

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