The resistances of 50 resistors are measured and the results recorded are as follows:
Resistance x Frequency
1.) 5 x 17,
2.) 5.5 x 12,
3.) 6 x 10,
4.) 6.5 x 6,
5.) 7 x 5)
Calculate standard deviation of the measurements
The Attempt at a Solution
Added up the frequences and got n = 50
Multiplied the resistance by its weight or frequency and got the following:
then I added the values up and divided the result by the sum of the frequencies (n) to get the mean (cant do an x bar so I'll denote it as M)
M = 5.7
If I follow the standard deviation formula and add up all results of (x - m)2 I get a really low number so if I then divide that really low number by n which is 50 I get something like 0.0049.
What am I doing wrong? Is the x of the formula resistance x frequency in this case since its weighted data Im dealing with?