You have a continuous random variable x, for which the mean µ equals 2.71.
you apply the transformation x* = 5 – 3x to the values of the random variable.
what is the mean of the transformed variable?

Since the random variable x is continuous, we can make use of linear operator
E(X*) = E(5 - 3X)
X* = E(5) - E(3X)
X* = 5 - 3E(X)
X* = 5 - 3(2.71)
X* = -3.13

The mean of the transformed variable is -3.13.

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.