The probability of an outcome that lies within 68% of the mean is a good indicator that it lies in which standard deviation? a. there is a probability that the outcome is within 3 standard deviations of the mean. b. standard deviations are not reliable, so the probability cannot be determined. c. there is a probability that the outcome is within 2 standard deviations of the mean. d. there is a probability that the outcome is within 1 standard deviation of the mean.