A traffic engineer needs to estimate the population mean num

A traffic engineer needs to estimate the population mean number of cars using Bumpy Avenue each day. Estimate the population mean using the following information:

Solution

Q3#
Standard Error= sd/ Sqrt(n)
Where,
sd = Standard Deviation
n = Sample Size

Standard deviation( sd )=26.6875
Sample Size(n)=89
Standard Error = ( 26.6875/ Sqrt ( 89) )
= 2.829

CI = x ± Z a/2 * (sd/ Sqrt(n))
Where,
x = Mean
sd = Standard Deviation
a = 1 - (Confidence Level/100)
Za/2 = Z-table value
CI = Confidence Interval
Point of estimate(x)=106.75
Standard deviation( sd )=26.6875
Sample Size(n)=89
Confidence Interval = [ 106.75 ± Z a/2 ( 26.6875/ Sqrt ( 89) ) ]
= [ 106.75 - 1.96 * (2.829) , 106.75 + 1.96 * (2.829) ]
= [ 101.205,112.295 ]

ANS:
Point of estimate(x)=106.75
Critical Value : 1.96
Std.Error = 2.829
Lower = 101.205
Upper = 112.295