Answer: 1.013
Step-by-step explanation:
Given the following data :
X_______f___fx___fx²
1_______15__15___15
2______30__60__120
3______28__84__252
4______10__40___160
______ 83__199__547
Number that is 1.5 standard deviations below the mean :
Mean(m) :
Σfx /Σf
(15 + 30 + 28 + 10) / 83
= 199 / 83
= 2.3976
Standard deviation(s) :
Sqrt[(Σfx² - (Σfx)²/Σf) /Σf-1]
sqrt[(547 - (199)²/83) / 83 - 1]
sqrt[(547 - (39601/83) / 82]
sqrt[(547 - 477.12) / 82]
sqrt(0.8522)
Standard deviation = 0.9231
1.5 standard deviations below the mean:
Mean - 1.5(standard deviation)
2.3976 - 1.5(0.9231)
2.3976 -1.38465
= 1.01295
= 1.013
