In a sample of 300 days, St. Petersburg has 171 foggy days. In an independent sample of 200 days, Stockholm has 92 foggy days. Compute the 95% CI for the difference between the two population proportions of foggy days.

By a small margin, Facebook remains the top choice of social media over all ages, with 29% using Facebook most often among those using social media sites. However, more visually oriented social networks such as Snapchat and Instagram continue to draw in younger audiences. When asked "Which one social networking brand do you use most often?" the results in the table show the top brands chosen by Americans aged 12-34 who currently use any social networking site or service. Social M edia Site Faceboo k Snapchat Instagra m Twitter Percentage That Use Most Often 29 28 26 6 20 (a) What is the sum of the percentages for these top social media sites? Give your answer as an exact number. Macmillan Learning top social media sites: What percent of Americans aged 12-34 use other social media sites most often? Give your answer as an exact number. other social media sites: do %

Suppose the prevalence of "dance fever" at a college is 40% among women and 10% among men. If there are half as many men as women, what is the overall prevalence of dance fever at the college? What proportion of people without dance fever at that college are women?

Consider the U.S. Electoral College System.  For each of the 50 states, determine the number of delegates received. Create a frequency table with 8 classes.

86% of Boston residents think chemistry is awesome. How many Boston residents would need to be sampled to find 1450 people who think chemistry is awesome?

a report about an isolated community claims there are more newborn females than males although we assume equal frequencies for each. Records indicate 628 boys and 718 girls born in the past month. what are Ho and Ha?

An interdepartmental task force is being formed to investigate an increase in violent crimes. 1/5 of the task force will be police officers from the local precinct. 1/4 will be ATF agents, and the remaining 22 will be from the FBI. How many people are participating in the task force?

A hospital report indicates 25% of its patients had an MRI in January. If 1,060 patients were hospitalized in January, how many had an MRI?

Suppose an internet marketing company wants to determine the current percentage of customers who click on ads on their smartphones. How many customers should the company survey in order to be 90% confident that the estimated proportion is within 2 percentage points of the true population proportion of customers who click on ads on their smartphones?