The smallest scale division of a stop watch is 0.1s. Calculate the possible error in the measurement of time recorded as 7.4s by an experimenter using the stop watch

Yep sounds good, so you'd better make a start.

One thing to think about here is that when you first start the watch it would read 0.0 until 0.1 seconds have transpired, then it shows 0.1 until 0.2 seconds have transpired, etc. So - what's the range of error? Can the watch's error be positive, or negative. or both?