There are 20 students in the drama club. Next year, 5
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Answer:
The answer is c) 761.0
Step-by-step explanation:
Mathematical hope (also known as hope, expected value, population means or simply means) expresses the average value of a random phenomenon and is denoted as E (x). Hope is the sum of the product of the probability of each event by the value of that event. It is then defined as shown in the image, Where x is the value of the event, P the probability of its occurrence, "i" the period in which said event occurs and N the total number of periods or observations.
The variance of a random variable provides an idea of the dispersion of the random variable with respect to its hope. It is then defined as shown in the image.
Then you first calculate E [x] and E [], and then be able to calculate the variance.
E[X]=88
So <em>E[X]²=88²=7744</em>
On the other hand
E[x²]=0+5+250+8250
<em>E[x²]=8505 </em>
Then the variance will be:
Var[x]=8505-7744
<u><em>Var[x]=761 </em></u>
