Answer:
a) 
b) The sample deviation is calculated from the following formula:

And for this case after replace the values and with the sample mean already calculated we got:

If we assume that the data represent a population then the standard deviation would be given by:

And then the deviation would be:

Step-by-step explanation:
For this case we have the following dataset:
67.401, 67.400, 67.402, 67.396, 67.406, 67.401, 67.396, 67.401, 67.405, and 67.404
Part a: Determine the most probable value.
For this case the most probably value would be the sample mean given by this formula:

And if we replace we got:

Part b: Determine the standard deviation
The sample deviation is calculated from the following formula:

And for this case after replace the values and with the sample mean already calculated we got:

If we assume that the data represent a population then the standard deviation would be given by:

And then the deviation would be:
