The force acting on a beam was measured under the same operating conditions and a sample of 5 data points was collected. This process was repeated by 3 observers. The pooled standard deviations of these 3 data sets was 1.21. Determine the true mean force using all pooled data (with a 95% probability). The result should look like this: True mean = mean +/- Margin of Error

± 1.51

Explanation:

The mean standard deviation = 1.21 since the three data sets had 1.21 standard deviations each

95% probability = 0.95

calculate standard error is calculated as = =

=  

=    =  =  0.6928

calculate the margin of error

from statistical table equation  becomes

2.179 * 0.6928 = 1.5096 ≈   ± 1.51

hypothesising or postulating

a.metals can become magnetic if they have many spinning electrons that create magnetic fields.d.only some metals are attracted by magnets; these metals are called ferromagnetic.

d.wrapping an insulated wire around a metal with ferromagnetic properties and applying an electric current.