Using the mtcars data set, determine the minimum value at 95% the confidence level for mean miles per gallon (mpg) for the population of four-cylinder cars. Put another way, fill in the blank: at 95% confidence, the mean miles per gallon for four-cylinder cars is at least _____ mpg. You may assume the population is normally distributed. Answer to at least one decimal place.

cyl=cylinder

hp am carb drat 93 62 gear 1 0 disp 4 108 4 146.7 4 140.8 4 78.7 4 4 1 1 1 1 95 cyl 22.8 24.4 22.8 32.4 30.4 33.9 21.5 27.3 0 4 M = M M - 66 1 4 4 52 1 1 4 4 65 1 4 75.7 71.1 120.1 79 1 1 1 1 4 97 0 3 4 st 66 1 1 4 1 26 4 120.3 91 1 5 2 wt 3.85 3.69 3.92 4.08 4.93 4.22 3.7 4.08 4.43 3.77 4.11 3.9 3.9 3.08 2.76 3.92 3.92 3.62 3.15 0 1 30.4 113 4 4 1 qsec VS 2.32 18.61 3.19 20 3.15 22.9 2.2 19.47 1.615 18.52 1.835 19.9 2.465 20.01 1.935 18.9 2.14 16.7 1.513 16.9 2.78 18.6 2.62 16.46 2.875 17.02 3.215 19.44 3.46 20.22 3.44 18.3 3.44 18.9 2.77 15.5 3.44 17.02 3.57 15.84 5 4 st 1 1 95.1 121 160 160 258 2 2 4 4 6 6 4 1 1 4 0 3 1 21.4 21 21 21.4 18.1 19.2 17.8 19.7 6 6 225 mpg Datsun 710 Merc 240D Merc 230 Fiat 128 Honda Civi Toyota Cor Toyota Cor Fiat X1-9 Porsche 91 Lotus Euro Volvo 142 Mazda RX4 Mazda RX4 Hornet 4D Valiant Merc 280 Merc 280C Ferrari Din Hornet Spc Duster 360 Merc 450SE Merc 45051 Merc 450SI Cadillac Fle Lincoln COI Chrysler In Dodge Cha AMC Javeli Camaro Z2 Pontiac Fir Ford Pante Maserati B 0 0 0 1 1 1 1 0 3 1 6 0 4 4 109 110 110 110 105 123 123 175 175 245 180 180 4 167.6 167.6 145 360 6 6 0 1 4 6 5 LD 00 18.7 0 0 3 2 360 3.21 0 3 4 14.3 16.4 17.3 co co 00 0 0 3.07 0 3 275.8 275.8 275.8 17.4 17.6 0 0 15.2 180 18 0 4.07 3.73 3.78 5.25 5.424 5.345 0 0 3 3 3 mmm + 0 4 10.4 10.4 14.7 00 00 00 205 215 0 0 3 3 230 0 0 4 472 460 440 318 304 350 0 0 3.07 3.07 2.93 3 3.23 2.76 3.15 3.73 3.08 4.22 3.54 8 8 2 3 3 0 17.98 17.82 17.42 16.87 17.3 15.41 17.05 14.5 14.6 0 2 0 0 15.5 15.2 13.3 19.2 15.8 15 3 4 150 150 245 175 264 335 8 8 3.52 3.435 3.84 3.845 3.17 3.57 400 0 3 2 co 00 00 0 0 1 5 4 351 301 0 1 5 8