Answer
With the outlier, the mean and standard deviation were 59.71 and 63.03, respectively.
Without the outlier, the mean and standard deviation were 51.25 and 50.97, respectively. Thus, removing the outlier reduces the mean by 8.46 seconds. Also, the standard deviation is reduced by 12.06 seconds.
Work Step by Step
$mean = (21+43+145+68+85+(-29)+90+66+27+110+61+229+(-14)+46+54+77+32+44+92+88+(-81))/21$
$mean = 1254/21$
$mean = 59.71$
$squared deviations (sd) = ((21-59.71)^2+(43-59.71)^2+(145-59.71)^2+(68-59.71)^2+(85-59.71)^2+((-29)-59.71)^2+(90-59.71)^2+(66-59.71)^2+(27-59.71)^2+(110-59.71)^2+(61-59.71)^2+(229-59.71)^2+((-14)-59.71)^2+(46-59.71)^2+(54-59.71)^2+(77-59.71)^2+(32-59.71)^2+(44-59.71)^2+(92-59.71)^2+(88-59.71)^2+((-81)-59.71)^2)/20$
$sd =((-38.71^2)+ (-16.71)^2)+(85.29^2)+(8.29^2)+(25.29^2)+
(-88.71)^2)+(30.29^2)+(6.29^2)+(-32.71)^2)+(50.29^2)+
(1.29^2)+(169.29^2)+((-73.71)^2)+((-13.71)^2)+
((-5.71)^2)+(17.29^2)+((-27.71)^2)+((-15.71)^2)+
(32.29^2)+(28.29^2)+((-140.71)^2))/20$
$sd = (1498.4641+279.2241+7274.3841+68.7241+639.5841+7869.4641+917.4841+39.5641+1069.9441+2529.0841+1.6641+28659.1041+5433.1641+187.9641+32.6041+298.9441+767.8441+246.8041+1042.6441+800.3241+19799.3041)/20$
$sd = 79456.2861/20$
$sd = 3,972.814$
$ s = \sqrt sd$
$ s = \sqrt 3972.814$
$ s = 63.03$
$mean = (21+43+145+68+85+(-29)+90+66+27+110+61+(-14)+46+54+77+32+44+92+88+(-81))/20$
$mean = 1025/20$
$mean = 51.25$
$squared deviations (sd) = ((21-51.25)^2+(43-51.25)^2+(145-51.25)^2+(68-51.25)^2+(85-51.25)^2+((-29)-51.25)^2+(90-51.25)^2+(66-51.25)^2+(27-51.25)^2+(110-51.25)^2+(61-51.25)^2+((-14)-51.25)^2+(46-51.25)^2+(54-51.25)^2+(77-51.25)^2+(32-51.25)^2+(44-51.25)^2+(92-51.25)^2+(88-51.25)^2+((-81)-51.25)^2)/19$
$sd =((-30.25^2)+ (-8.25)^2)+(93.75^2)+(16.75^2)+(33.75^2)+
(-80.25)^2)+(38.75^2)+(14.75^2)+(-24.25)^2)+(58.75^2)+
(9.75^2)+((-65.25)^2)+((-5.25)^2)+(2.75^2)+(25.75^2)+((-19.25)^2)+((-7.25^2)+(40.75^2)+(36.75^2)+((-132.25)^2))/19$
$sd =(915.0625+68.0625+8789.0625+280.5625+1139.0625+6440.0625+1501.5625+217.5625+588.0625+3451.5625+95.0625+4257.5625+27.5625+7.5625+663.0625+370.5625+52.5625+1660.5625+1350.5625+17490.0625)/19$
$sd = 49365.75/19$
$sd = 2598.19$
$ s = \sqrt sd$
$ s = \sqrt 2598.19$
$ s = 50.97$
