o, the probability that you get the first 1 in at most 20 rolls.

oAn approximation ofusing the first 20 values for X, namely.

oAn approximation to the variance of X using the first 20 terms, for this use and then use this and the above to get a rough approximation .

Use the preceding to approximate the standard deviation using the first 20 terms.o, the probability that you get the first 1 in at most 20 rolls.

P(X=1)

oAn approximation ofusing the first 20 values for X, namely.

oAn approximation to the variance of X using the first 20 terms, for this use and then use this and the above to get a rough approximation .

Use the preceding to approximate the standard deviation using the first 20 terms.