We assume that the height of Hong Kong people obeys Gaussian distribution with m and m. In door design of public buses, it is required that the door's height should be no less than the height of 90% Hong Kong people. Determine the height of the door. Assume that F(1.2816) = 0.9 where F(x) is the CDF of a standard normal random variable.

A chain of restaurants has historically had a mean wait time of 5 minutes for its customers. Recently, the restaurant added several very popular dishes back to their menu. Due to this, the manager suspects the wait time, μ, has increased. He takes a random sample of 35 customers. The mean wait time for the sample is 5.1 minutes. Assume the population standard deviation for the wait times is known to be 1.1 minutes. Can the manager conclude that the mean wait time is now greater than 5 minutes? Perform a hypothesis test, using the 0.10 level of significance. (a) State the null hypothesis Ho and the alternative hypothesis H₁. Ho: O H₁:0 μ X 0° OO 20ם ローロ OO × 5 (b) Perform a hypothesis test. The test statistic has a normal distribution (so the test is a "Z-test"). Here is some other information to help you with your test. 0.10 is the value that cuts off an area of 0.10 in the right tail. *-μ ⚫ The test statistic has a normal distribution and the value is given by z=- σ √n Standard Normal…

Coal is carried from a mine in West Virginia to a power plant in New York in hopper cars on a long train. The automatic hopper car loader is set to put 70 tons of coal into each car. The actual weights of coal loaded into each car are normally distributed, with mean u = 70 tons and standard deviation o = 1.4 ton. n USE SALT (a) What is the probability that one car chosen at random will have less than 69.5 tons of coal? (Round your answer to four decimal places.) (b) What is the probability that 30 cars chosen at random will have a mean load weight x of less than 69.5 tons of coal? (Round your answer to four decimal places.) (c) Suppose the weight of coal in one car was less than 69.5 tons. Would that fact make you suspect that the loader had slipped out of adjustment? O Yes O No Suppose the weight of coal in 30 cars selected at random had an average x of less than 69.5 tons. Would that fact make you suspect that the loader had slipped out of adjustment? Why? O Yes, the probability that…

Suppose that average rainfall in your city is normally distributed, and for the past 36 months, the rainfall has been 0.5 inches per day on average with a standard deviation of 0.16. Let x be a random variable that has a normal distribution and represents the rainfall in inches per day. Using a 0.05 level of significance, you want to test the hypothesis that monthly rainfall has been 0.7 inches per day on average. What conclusion do you make from your test? Select one: a. Reject H0; the average rainfall is not 0.5 inches. b. Reject H0; the average rainfall is not 0.7 inches. c. Do not reject H0; the average rainfall is still 0.5 inches. d. Do not reject H0; the average rainfall is still 0.7 inches.

The weights of parcels that are dropped off at a local shipping center can be represented by a random variable X that is normally distributed with mean µx=70 and standard deviation ox=10. Determine the following: %3D What is P [X < 60] = ? %3D Select one: O a. 0.8675 O b. 0.1587 O c. 1.2345

A population has a mean of 300 and a standard deviation of 40. Suppose a simple random sample of size 100 is selected and x¯ is used to estimate μ .What is the probability that the sample mean will be within +/- 5 of the population mean?

In the manufacture of steel rollers to fit an assembly, the external diameter is considered to be a random variable with mean equal to 23 mm and variance equal to 0.0036 cm2. 1.5 is supported standard deviations more than the mean and 3.5 standard deviations below average. A piece with a diameter below such specifications is considered waste, whereas a piece with a diameter larger than specified must be reprocessed. Which is the percentage of pieces that:to. They are being wasted.b. They need to be reprocessed.c. Acceptable.d. If you want to establish that the reprocessing is 5% of the rollers and waste of 1%, than specification limit would recommend.