molar mass i need help...please?

Question

The molar mass of a compound is measured to be 33.4, 35.2, 34.1 and 33.9 g/mol in four trials

a) what is the average molar mass of the compound

b) calculate the standard deviation for the determination of the molar mass


for A would I add the 4 number and divide by 4?

Answer 1

for A yes that's all you would do,

for the standard deviation, you need to find the difference between each individual sample measurement, and square them. Then find the mean or average of these squared values, and take the square root of this number. This is the standard deviation. However, if you take the numbers you gave and put them on an EXCEL table and use the std dev formula, you get a different answer than the one I get when I use the instructions a gave you (that I found on the link below). Not sure what the explanation is....