回答:
#2.55(3秒)#
説明:
#{-7, 12, 14, 8, -10, 0, 14}#
平均:
#(-7+ 12+ 14+ 8+ -10 + 0+ 14)/7#
#=31/7#
各数の偏差を見つける(#n#-平均):
#-7 - 31/7 =- 49/7 - 31/7 = 80/7#
#12 - 31/7 = 84/7 - 31/7 = 53/7#
#14 - 31/7 = 98/7 - 31/7 = 67/7#
#8 - 31/7 = 56/7 - 31/7 = 25/7#
#-10 - 31/7 = -70/7 - 31/7 = -101/7#
#0 - 31/7 = -31/7#
#14 - 31/7 = 98/7 - 67/7 = 32/7#
分散=偏差の平均
#(80/7 +53/7+ 67/7+ 25/7 -101/7 -31/7 +32/7)/7#
#=125/49#
#= 2.55(3秒)#