n=51
=20.6
=8.9
#95% Confidence interval for the true mean speed is
(-Z/2*/sqrt(n)<<+Z/2*/sqrt(n))
At 95% Z/2 ie Z0.05/2=Z0.025=1.96
(20.6-1.96*8.9/sqrt(51)<<20.6+1.96*8.9/sqrt(51))
(20.6-2.44<<20.6+2.44)
(18.16<<23.04)
95% Confidence interval for the true mean speed is between 18.16 and 23.04
Question 19 8 pts A city planner is researching why traffic speeds appear to be slower...