The piano wire 0.5 metre long has a total mass of 0.01 kg and in strectched at the tension of 800 Newton. calculate the frequency of the wire when it sound its fundamental note

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