How much percent of the earth's water is drinkable?

Why are some galaxies’ spectra blueshifted rather than redshifted? question 4 options:

Ais useful when you need a simple machine to you separate two things. a. lever b. screw c. pulley d. wedge

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