A luxury furniture manufacture will make custom furniture for their customers. Pricing is based on the number of hours of skilled labor it takes to make a piece. The time it takes to make a custom couch is normally distributed with an average of 280 hours and a standard deviation of 40 hours.     What percent of custom couches take 255 hours or less to make?        How long would it take to build a couch that is in the 95th percentile?

Most water treatment facilities monitor the quality of their drinking water on an hourly basis. One variable measured is pH, which measures the degree of alkalinity or acidity in the water. A pH below 7.0 is acidic, one above 7.0 is alkaline, and a pH of 7.0 is neutral. One water-treatment plant has a target pH of 8.5. (Most try to maintain a slightly alkaline level) The mean and standard deviation of 1 hour’s test results based on 49 water samples at this plant are:   = 8.42; s = 0.16 Does this sample provide sufficient evidence that the mean pH level in the water differs from 8.5?  do in excel if needed

The highway mileage (mpg) for a sample of 8 different models of a car company can be found below. Find the mean, median, mode, and standard deviation. Round to one decimal place as needed. 20, 23, 25, 28, 30, 32, 35, 35 Mean = Median = %3D Mode = Standard Deviation =

With the extra data value,  the range, standard deviation, and variance is?

Use the Empirical Rule. The mean speed of a sample of vehicles along a stretch of highway is 71 miles per hour, with a standard deviation of 3 miles per hour. Estimate the percent of vehicles whose speeds are between 62 miles per hour and 80 miles per hour. (Assume the data set has a bell-shaped distribution.) Approximately % of vehicles travel between 62 miles per hour and 80 miles per hour.

The ages in years of a random sample of shoppers at a gamming store are shown. 12, 17, 23, 13, 20, 16, 20, 18, 13, 18. Find the range, mean, variance and standard deviation.

Four students take tests.  The results of each test for the class and the student are listed in the choice.  Which student has the highest Z Score? a.John who scored an 85 and whose class averages 77 with a standard deviation of 4. b.Tammy who scored an 86 and whose class averages 82 with a standard deviation of 3. c.Rob who scored an 87 and whose class averages 73 with a standard deviation of 11. d.Sandra who scored a 90 and whose class averaged an 81 with a standard deviation of 7.

State whether one would expect the data set described below to be normally distributed. Explain why or why not. The genders of 1,000 randomly selected adults

Use the Empirical Rule. The mean speed of a sample of vehicles along a stretch of highway is 63 miles per hour, with a standard deviation of 4 miles per hour. Estimate the percent of vehicles whose speeds are between 59 miles per hour and 67 miles per hour. (Assume the data set has a bell-shaped distribution.) Approximately % of vehicles travel between 59 miles per hour and 67 miles per hour.

The average birth weight of elephants is 230 pounds. Assume that the distribution of birth weights is Normal with a standard deviation of 50 pounds. Find the birth weight of elephants at the 90th percentile.