An environmental scientist developed a new analytical method for the determination of cadmium (cd^2+) in mussels. to validate the method, the researcher measured the cd^2+ concentration in standard reference material (srm) 2976 that is known to contain 0.82 plusminus 0.16 ppm cd^2+. five replicate measurements of the srm were obtained using the new method, giving values of 0.782, 0.762, 0.825, 0.838, and 0.761 ppm cd^2+. calculate the mean (bar x), standard deviation (s_x), and the 95% confidence interval for this data set. at list of t values can be found in the student's t table. x bar = s_x = 95% confidence interval = x bar plusminus does the new method give a result that differs from the known result of the srm at the 95% confidence level?

The method is accurate  in the calculation of the

Explanation:

As a first step we have to calculate the average concentration of find it by the method.

Then we have to find the standard deviation:

For the confidence interval we have to use the formula:

μ=Average±

Where:

t=t student constant with 95 % of confidence and 5 data=2.78

μ=  ±  

upper limit:  0.84

lower limit: 0.75

If we compare the limits of the value obtanied by the method (Figure 1 Red line) with the reference material (Figure 1 blue line) we can see that the values obtained by the method are within the values suggested by the reference material. So, it's method is accurate.

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).