A researcher is interested in finding a 90% confidence interval for the mean number of times per day that college students text. The study included 122 students who averaged 25.2 texts per day. The standard deviation was 14.7 texts. Round answers to 3 decimal places where possible. a. To compute the confidence interval use a V distribution.

Researchers collected information on the body parts of a new species of frog. The thumb length for the female frog has a mean of 8.28 mm and a standard deviation of 0.78 mm. Let x denote thumb length for a female specimen.   a. Find the standardized version of x. b. Determine and interpret the​ z-scores for thumb lengths of 10.3 mm and 7.1 mm. Round your answers to two decimal places.   a. Find the standardized version of x.   z=enter your response here

Suppose we wish to calculate a 90% confidence interval for the average amount spent on books by freshmen in their first year at a major university. The interval is to have a margin of error of $2. Assume that the amount spent on books by freshmen has a normal distribution with a standard deviation of $30. How many observations are required to achieve this margin of error?

A researcher is interested in finding a 90% confidence interval for the mean number of times per day that college students text. The study included 149 students who averaged 34.2 texts per day. The standard deviation was 18.6 texts. Round to 3 decimals. b. With 90% confidence the population mean number of texts per day is between _______ and ________ texts a day.

The 95% confidence interval of the variance of a population is computed as (12.367,21.761). Interpret this confidence interval.

Researchers measured the data speeds for a particular smartphone carrier at 50 airports. The highest speed measured was 71.7 Mbps. The complete list of 50 data speeds has a mean of x = 15.45 Mbps and a standard deviation of s = 21.16 Mbps. a. What is the difference between carrier's highest data speed and the mean of all 50 data speeds? b. How many standard deviations is that [the difference found in part (a)]? c. Convert the carrier's highest data speed to az score. d. If we consider data speeds that convert to z scores between -2 and 2 to be neither significantly low nor significantly high, is the carrier's highest data speed significant? a. The difference is Mbps. (Type an integer or a decimal. Do not round.)

A researcher is interested in finding a 98% confidence interval for the mean number of times per day that college students text. The study included 110 students who averaged 33.1 texts per day. The standard deviation was 16.8 texts. Round answers to 3 decimal places where possible

Use z scores to compare the given values. The tallest living man at one time had a height of 252 cm. The shortest living man at that time had a height of 53.2 cm. Heights of men at that time had a mean of 172.68 cm and a standard deviation of 8.46 cm. Which of these two men had the height that was more extreme? see score past due Since the z score for the tallest man is z=] and the z score for the shortest man is z= the height that was more extreme. (Round to two decimal places.)

A recent survey of 25 students showed that they spent an average of $18.53 on petrol eachweek. The standard deviation of the sample was $3.00. Find the 99% confidence intervalfor the true mean (average over all students).

Karen wants to advertise how many chocolate chips are in each Big Chip cookie at her bakery. She randomly selects a sample of 78 cookies and finds that the number of chocolate chips per cookie in the sample has a mean of 19.3 and a standard deviation of 2.1.   Find a 80% confidence interval for the number of chocolate chips per cookie for Big Chip cookies?   Round your answers to one decimal place.