<prompt> 3 Standard deviation from mean covers how much areas under normal distribution curve-63-666-69599  <response>: Ans. is d i.e., 99 Area under standard normal distribution curve It can be understand by the 68-95-99.7 rule -i The area between one standard deviation on either side of the mean x - 1 o will include 68 percent of the values.ii The area between two standard deviations on either side of the mean will cover 95 of values.iii The area between three standard deviation will include 99.7 of values. These limits on either side of the mean is called confidence limits. For example, if we are considering the 95 percent confidence limits Area under 2 SD, that means that 95 of the values in the distribution will be included between the limits 2 SD x - 2 a. Therefore, the probability of a reading falling outside confidence limit 95 is only 5, i.e. 1 in 20 P 0.05. So,For 1 SD, confidence limit - 68For 2 SD, confidence limit - 95For 3 SD, confidence limit - 99.7 