Calculate the 99 percent confidence interval for the differe

Calculate the 99 percent confidence interval for the difference of the mean tensile strength of the two textiles.

Solution

CI = x1 - x2 ± t a/2 * Sqrt ( sd1 ^2 / n1 + sd2 ^2 /n2 )
Where,
x1 = Mean of Sample 1, x2 = Mean of sample2
sd1 = SD of Sample 1, sd2 = SD of sample2
a = 1 - (Confidence Level/100)
ta/2 = t-table value
CI = Confidence Interval
Mean(x1)=32
Standard deviation( sd1 )=1.291
Sample Size(n1)=7
Mean(x2)=35
Standard deviation( sd2 )=1.414
Sample Size(n1)=6
CI = [ ( 32-35) ±t a/2 * Sqrt( 1.666681/7+1.999396/6)]
= [ (-3) ± t a/2 * Sqrt( 0.57) ]
= [ (-3) ± 4.032 * Sqrt( 0.57) ]
= [-6.05 , 0.05]