Answer Happy

DATA
Suppose in an industrial experiment that an engineer is interested in how the mean absorption of moisture in concrete varies among 5 different concrete aggregates. The samples are exposed to moisture for 48 hours. It is decided that 6 samples are to be tested for each aggregate, requiring a total of 30 samples to be tested. The data are recorded in the file concrete_data.csv.
(i) (ii) Normal distributions with equal variances are used for the concrete aggregates. Normal distributions with unequal variances are used for the concrete aggregates. Write down the null and alternative hypotheses clearly for each of the above cases, and then draw a conclusion with evidence at a 0.03 level of significance. Use R to answer this question. [To load the data file into R, you can use read.csv(). You may also find the following R functions useful: as.factor() to set the type of a vector as a factor, rep() generate vector with repeated elements, seq() generate a sequence of consecutive numbers, data.frame() create a dataframe from variables.]
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