F.2 maths question need step

because i do not know well about error so i have some question problem

1. the time taken by a train to go from station A to station B is 3 minutes 49
seconds. express the time in minutes and seconds.

2. estimate the value of numerical expression 308.8-5.9513 除0.02038 by first
rounding off each number to 1 sig.fig

3. the number of heartbeats per minute of a humming-bird measured by a biologist is 980, and the relative error is 245分之1 . what is the possible range of the number of heartbeats per minute?

4.by using a stopwatch, peter finds that the time taken for a colour printer to print
100 identical documents is 7 minutes 5 seconds, and the relative error is 85分之1. what is the possible range of time required to print 1 document?

5.the maximum pulling strength of a fishing-line measured by a laboratory is 60kg and the percentage error is 5%. what is the possible range of the maximum
pulling strength of the fishing-line?

6. the time required for an anti-virus software to scan all the files of the computer is measured by a programmer to be 19 minutes 15 seconds, collect to the
nearest 5 seconds. find the percentage error of the measured time correct to 2
sig.fig

7. an observatory records that the Leo meteor shower appears every 33 years,
collect to the nearest 0.5 year, and the Halley's comet returns every 76 years,
collect to the nearest year.
(a) find the percentage error for each of these recorded times, collect to 2 sig.fig.
(b) the measurement of the (Leo meteor shower/ Halley's comet) is more
accurate.


Thank you for your help :)