Alexander a meteorologist is studying the daily high tempera

Alexander, a meteorologist, is studying the daily high temperatures over the past 50 years during the month of July for the cities of Chicago and Phoenix (a sample size of 1550 July days for each city). Alexander found that in Chicago, the middle 95% of July days have a high temperature between 70 degree F and 98 degree F, while in Phoenix, the middle 95% of July days have a high temperature between 94 degree F and 110 degree F. On one particular July day, the temperature in Phoenix is exactly 17 degree F higher than the temperature in Chicago. Which of the following is not a valid pair of z-scores for the two cities? Circle your answer. Chicago: z = 1.7143 Chicago: z = D?8571 Phoenix: z = -3.2500 Phoenix x: = 1.2500 Chicago: z = 0.4286 Chicago: z = 15714 Phoenix: z = 0.7500 Phoenix: z = 2.5000 A polling company defines a \"likely voter\" as someone who has voted in each of the previous two elections. The company asks 815 likely voters which candidate they support in the upcoming election. Find the margin of error for the Poll to the nearest tenth of a percent.

Solution

A Z-score tells you “how many standard deviations a value is from the mean”

z= x - mu / sigma where mu is mean , sigma is standard deviation ,put aalthe values and get d ans

z chicago = 98-(86)/28=0.4286

z phoenix = 110-98/ 12 =0.75

. A margin of error of plus or minus 3 percentage points at the 95% confidence level means that if we fielded the same survey 100 times, we would expect the result to be within 3 percentage points of the true population value 95 of those times.