A health psychologist was interested in the effects of vitamin supplements on the immune system. Three groups of adults were exposed (in a highly ethical way) to the cold virus; one group took no supplements for a week before exposure, another had vitamin C supplements, and a third had multivitamins (excluding C). The severity of the cold was measured as a percentage (0% = not contracted, 100% very severe symptoms). The psychologist also measured the number of cigarettes that each person smoked per day, as smoking suppresses the immune system. The psychologist was interested in the differences in the severity of the illnesses across different vitamin groups accounting for cigarette usage. What technique should be used to analyse these data? A. Two-way repeated-measures ANOVA B. Two-way independent ANOVA 

In a normal distribution, a data value located 1.4 standard deviations below the mean has Standard Score: \( \mathrm{z}=-1.4 \) In a normal distribution, a data value located 2.3 standard deviations above the mean has Standard Score: \( \mathrm{z}=2.3 \) In a normal distribution, the mean has Standard Score: \( \mathrm{z}=\square \)

A set of exam scores is normally distributed with a mean \( =74 \) and standard deviation \( =8 \). \( 95 \% \) of the data values lie between 58 \( \% \) of the exam scores are between 66 and 74 . \( \% \) of the exam scores are between 74 and 90 . \( \% \) of the exam scores are between 82 and 90 . \% oxam scores are greater than or equal to 66 .

A variable \( x \) is normally distributed with mean 21 and standard deviation 5. a) Determine the \( z \)-score for \( x=27 \). b) Determine the \( z \)-score for \( x=15 \). c) What value of \( x \) has a \( z \)-score of 1.8 ? \( x=x= \) d) What value of \( x \) has a \( z \)-score of -0.6 ? e) What value of \( x \) has a \( z \)-score of 0 ? \( x= \)

1.3.1 Bereken die gemiddelde aantal huishoudings in Suid-Afrika wat gedurende 2022 nie toegang tot die internet gehad het nie.

Which of the following statements are TRUE about the normal distribution? Check all that apply. The area to the left of a z-score plus the area to the right of that same z-score will always equal 1 . A data value with z-score \( =-1.5 \) is located 1.5 standard deviations below the mean. The Empirical Rule only applies when a value is exactly 1,2 , or 3 standard deviations away from the mean. A z-score is the number of standard deviations a specific data value is from the mean of the distribution.