a) P (x >120) ="1-p(z<\\tfrac {120-75} {15})=1-P(z<3)=1-0.9987 =0.0013"
b) P(x<k) = "p(z< \n\\frac\n{k\u221275} {15}\n\u200b\t\n )=0.09,therefore,z=\u03d5(0.09)=\u22121.341"
"\\frac {k\u221275}{15}\n =\u22121.341,therefore, k=75+15\u2217(\u22121.341)= 54.885 minutes"
c) mean = median = "0.5*75 +10 =47.5"
standard deviation =0.5*15 = 7.5
Variance = "7.5^2 =56.25"
d) Margin of error = z* SD = 1.645*7.5= 12.34
L1 = "47.50-12.34=35".16
L2 = "47.50 + 12.34 = 59.84"
Comments
Leave a comment