An industrial concern has experimented with several different mixtures of the four components€”magnesium, sodium nitrate, strontium nitrate, and a binder€”that comprise a rocket propellant. The company has found that two mixtures in particular give higher flare-­illumination values than the others. Mixture 1 consists of a blend composed of the proportions .40, .10, .42, and .08, respectively, for the four components of the mixture; mixture 2 consists of a blend using the proportions .60, .25, .10, and .05. Twenty different blends (10 of each mixture) are prepared and tested to obtain the flare-illumination values. These data appear here (in units of 1,000 ­candles).

a. Plot the sample data. Which test(s) could be used to compare the mean illumination values for the two mixtures?
b. Give the level of significance of the test and interpret your findings.

Mixture 1 185 192 20 215 170 190 175 172 198 202 Mixture 2 22 210 215 202 20 196 225 230 214 217