Fifty children were diagnosed with leukemia during the past year. The weight of each child was recorded (in pounds) at the time of diagnosis. Listed are the weights listed from lightest to heaviest: 20, 22, 23, 26, 27, 28, 28, 29, 30, 31, 31, 32, 33, 34, 35, 37, 38, 39, 40, 41, 42, 42, 43, 43, 44, 45, 47, 48, 48, 49, 49, 51, 52, 52, 52, 54, 55, 56, 58, 58, 58, 60, 61, 62, 63, 64, 65, 67, 68, 70.

1. Calculate the mean, median, and mode.
2. Calculate the variance and standard deviation computed from a frequency distribution with a class interval of one.
3. Calculate the weights that are one standard deviation above and one standard deviation below the mean.
4. Calculate the weights that are two standard deviations above and two standard deviations below the mean.