54 Question School administrators wondered how class size affected the average class mark (\%) achieved by students. Using a random sample of classes, the following linear regression line was found: \[ y=98.06-0.55 x \] Using this linear regression line, predict the average class mark of a class with 25 students in it. a) 84.31 b) 91.06 c) 72.51 d) 111.81 e) None of the above

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

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 greater than or equal to 66 .

A variable is normally distributed with mean 18 and standard deviation 9 . Use your graphing calculator to find each of the following areas. Write your answers in decimal form. Round to the nearest thousandth as needed. a) Find the area to the left of 17.

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 ? \( x= \)

EJERCICIO 7 -1 Se muestran las tallas de calzado de los últimos 20 clientes que han entrado a una zapatería \[ \begin{array}{l}25,22.5,26,26.5,27,25,23,24,24,23,24,24.5,24.5,24,23.5,24.5 \\ 23.5,24.5,25,23.5\end{array} \] Ordena las tallas y elabora una gráfica de columnas para representar los datos