Random variables Given independent random variableswith means and standard deviations as shown, find themean and standard deviation of:a) 2Y + 20b) 3Xc) 0.25X + Yd) X - 5Ye) X1 + X2 + X3 Mean SDX 80 12Y 12 3

Assume that we have estimated the standard deviation of a sample x₁,. ., xn ER using the sample standard deviation s = ô(x₁,x2,...,xn). What does ô(−2x1, −2x2,..., -2xn) equal? A: s B: -4s C: 4s D: -2s E: 2s

Suppose that the contagious period of COVID-20 has an average of 7 days, and follows a chi-square distribution.  Let X measure the contagious period for a randomly selected specimen of the COVID-20 virus. State the distribution of the random variable X. Group of answer choices X∼χ2(6) X∼Student′st(7) X∼χ2(7) X∼Continuous(7)     A friend of yours has COVID-20 and the doctors have told her that she has had it for 10 days.  Compute the probability that they are still contagious.  (I.E. compute the probability that X is greater than or equal to 10 days.)

In order to use the defining formula for variance, we must calculate  (x − x)2  for each data value in the data set  14, 18, 22, 26, 33.  Use the values in the data set and the mean  x = 22.6  to fill out the following table. x 14 18 22 26 33 x 22.6 22.6 22.6 22.6 22.6 x − x 14 − 22.6 = −8.6 18 − 22.6 = __________ 22 − 22.6 = −0.6 26 − 22.6 = _________ 33 − 22.6 = 10.4 (x − x)2 73.96 __________ 0.36 ________ 108.16