A market researcher analyzed how many electronics devices customers buy in a single purchase. The distribution has a mean of three with a standard deviation of 0.7. She samples 400 customers. What is the z score for Σx= 1,172? (Enter an exact number as an interference, fraction, or decimal.)

Assume that the mathematics scores on the SAT are normally distributed with a mean of 500 and a standard deviation of 100. What percent of students who took the test have a mathematics score below 610​?

A community college Math instructor feels that the average age of community college students decreased since they started teaching 25 years ago.  Looking up data from the year the instructor started teaching, the mean age of community college students was 24.3 years old, with a population standard deviation of 2.2 years.  The Math instructor took a sample of 40 of their current community college students and found that the sample had a mean age of 23.7 years old.  Assume the population of ages of community college students is normally distributed and that the population standard deviation has remained the same. Test at the 5% significance level if the mean age of community college students is now less than 24.3 years old. Choose the correct answer from the parenthesis. (i)  Hypotheses       ?0:   ?  =  ( 0, 2.2, 22.7, 24.3, 25, 40) ______________ .     ?1:    ?  =  ( < , > ) ______________   ( 0, 2.2, 22.7, 24.3, 25, 40) ________________ . (ii)  Test Statistic     ( z/ t )…

According to the U.S. Census, the average adult woman is the United States is 65 inches tall and the standard deviation is 3 inches.  If Zsike is 67 inches tall, what is her z-score?