In a survey, 30 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $33 and standard deviation of $2. Find the margin of error at a 99% confidence level. Give your answer to two decimal places.

A mechanic sells a brand of automobile tire that has a life expectancy that is normally distributed, with a mean life of 29,000 miles and a standard deviation of 2100 miles. He wants to give a guarantee for free replacement of tires that don't wear well. How should he word his guarantee if he is willing to replace approximately 10% of the tires? Click to view page 1 of the table. Click to view page 2 of the table. Tires that wear out by miles will be replaced free of charge. (Round to the nearest mile as needed.)

Juan and his family are relocating to Los Angeles. They purchased a home they really like, which cost $739,000 . The mean home price in the area is $ 735,000 with a standard deviation $17,050 . Find the z-score of the price of Juan's home relative to the prices among all the homes in the area. Round your answer to two decimal places. z=

The prices of all college textbooks follow a bell-shaped distribution with a mean of $108 and a standard deviation of $21. What percentage of the price that is more than 140? Show your works and read the table.

Max scored an 80 on her psychology quiz, but the class as a whole averaged a 40. If the standard deviation was 10, what was Alicia's z-score?

On a multiple choice test with 10 questions, each question has four possible answers, one of which is correct. For students who guess at all answers, find the standard deviation for the number of correct answers.

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?

On the past mathematics test, the bottom 20% of students failed to pass the test. The mean for the test was 55 and the standard deviation was 11. what was the passing score

Jasmine, Jamal, and Jessa all got the same mean grade (2.7) on their quizzes last semester. The standard deviations were 0.5 for Jamal, 1.1 for Jessa, and 0.2 for Estrella. Which student received the highest grades from the quizzes?

According to the National Association of Realtors, it took an average of three weeks to sell a home in 2017. Data for the sale of 40 randomly selected homes sold in Greene County, Ohio, in 2017 showed a sample mean of 3.6 weeks with a sample standard deviation of 2 weeks. Conduct a hypothesis test to determine whether the number of weeks until a house sold in Greene County differed from the national average in 2017. Round your answer to four decimal places. p-value = Use a = 0.05 for the level of significance, and state your conclusion. I. Reject Hn. There is a statistically significant difference between the national average time to sell a home and the mean time to sell a home in Greene County. II. Reject Hn. There is not a statistically significant difference between the national average time to sell a home and the mean time to sell a home in Greene County. (II. Do not reject Ho. There is a statistically significant difference between the national average time to sell a home and the…