Question

An aircraft designer has theorical evidence that painting the airplane reduces its speed at a specified power and flap setting. He tests six consecutive airplanes from the assembly line before and after painting. The results are shown below: Airplane antwN- Top Speed (mph) Painted Not Painted 286 289 285 286 279 283 283 288 283 286 281 289 Find a 95% confidence in interval for the mean difference? Assuming the differences to be approximately normally distributed. 15 pts

Answer 1

68% 12:46 Book (10) Ap fx в A B P D E F G Not Painted X1 bar 283.33 Formula = average 1 Painted s1 289 2.88 Formula stdev.s 2 286 Painted n1 3 285 286 6 4 279 283 286.33 Formula average 2.80 Formula = stdev.s X2 bar 5 283 288 283 Not Painted s2 6 281 289 n2 7 286 6 24 95% C.I is Upper end point Lower end point 25 -5.97 -0.03 26 27 t* (n1+n2-2 = 10, 0.05) 1.812 28 29 32 33 34 S12 + n2 35 Lower bound: (X1 - X2) - ta/2 36 |n1 37 38 39 40 12 + n2 41 Upper bound: (X1 - X2) + ta/2 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 11 67 ca EL