Problem regarding the excessive variance

Reference no: EM131000819

The intrinsic variations in the measured amount of pollution contained in water samples from rivers and streams in a mining region of West Central United States is known to be a normally distributed random variable with a fairly stable standard deviation of 5 milligrams of solids per liter. As an EPA inspector who wishes to test a random selection of n water samples in order to determine the mean daily rate of pollution within ±1 milligram per liter with 95% con?dence, how many water samples will you need to take? A selection of 6 randomly selected water samples returned a mean value of 40 milligrams per liter and what seems like an excessive variance of 30 (mg/liter)2 . Determine a 95% con?dence interval around this estimate of σ2 and comment on whether or not this value is excessive compared to the assumed population value.

Reference no: EM131000819

Questions Cloud

What rate does the pump supply heat to the building : A perfectly reversible heat pump supplies to a building to maintain its temperature at 27oC. The cold reservoir is a river at 7oC. If work is supplied to the pump at the rate of 1 kW, at what rate does the pump supply heat to the building?

Show that the angle dbx is equal to the angle xbl : Let ABC be a triangle such that angle B is a right angle. Let L be the midway point of the side AC. Show that the angle DBX is equal to the angle XBL.

What is the mass of the unknown mass in kg : you performed an experiment with a spring to find the mass of an "unknown mass." If the spring constant is 9.94 N/m and the "unknown mass" caused a displacement of Δ16.1 cm, what is the mass of the "unknown mass" in kg?

What angular speed would we have to spin the coil : One way to do this would be to spin a metal loop about an axis perpendicular to Earth's magnetic field. Suppose that the metal loop is a square that is 45.0 cm on each side and that we want to generate a potential in the loop of amplitude 125 V at..

Problem regarding the excessive variance : A selection of 6 randomly selected water samples returned a mean value of 40 milligrams per liter and what seems like an excessive variance of 30 (mg/liter)2 . Determine a 95% con?dence interval around this estimate of σ2 and comment on whether or..

Find a minimal vertical distance from level of person eyes : A person is 1.7 m tall. Where should he place the top of a mirror on the wall so he can see the top of his head? Assume his eyes are 4.5 cm below the top of his head. Find a minimal vertical distance from the level of the persons eyes to the top o..

Appropriate probability model for the phenomenon : Postulate an appropriate probability model for the phenomenon in question, treat the data set as three random samples of size n = 10 each, from the three different populations represented by each operator.

Frequency of accidents occurring : The data below, taken from Greenwood and Yule, (1920)3 , shows the frequency of accidents occurring, over a ?ve-week period, to 647 women making high explosives during World War I.

Evaluate the inner product of the hilbert-transform pair : Find the Hilbert-transform pair, find the average power of the Hilbert-transform pair and evaluate the inner product of the Hilbert-transform pair.

User Account

All Pages