The length of a human pregnancy follows a Normal distribution with a mean of 266 days and a standard deviation of 16 days a. Find the probability that a randomly selected woman will have a pregnancy of less than 258 days.
b. Find the mean and new standard deviation of the sampling distribution of the mean length of pregnancy for an SRS of 80 women.
(Note: I already know part a, I just can't get the right standard deviation for part b)

In a newspaper, it was reported that yearly robberies in springfield were up 25% to 265 in 2013 from 2012. how many robberies were there in springfield in 2012?

Stu and ambrose are working together on a study of whether diet is related to students' mental health. first, they randomly select 10 students from the student center and 10 students from the office of counseling and psychological services. then, they ask students to rate their diet in terms of healthiness on a scale of 1-100 before completing a 20-item mental health survey. a) name one of the constructs being studied b) how was the construct you named above operationally defined in this experiment? e) was the variable you described above their independent variable, their dependent variable, or a controlled variable? d) what is a confounding variable? what is a potential confound in this study?

When a number is decreased by 9.9% the result is 40. what is the original number to the nearest tenth? super urgent