Upper and lower bounds stopwatches

Question

Question: what was the winners max time? If one of the stopwatches was faulty which one would it be to make it possible for the winner to win in 12.6 seconds

Info:

Three friends timed a race using stopwatches which record time to different degress of accuracy.

All stopped when the winner reached the finish line.

Jane's read 12.5 seconds to the nearest 0.5 seconds.

Keith's read 13 seconds correct to the nearest seconds

Lana's read 12.7 seconds correct to the nearest tenth of a second.

Answer 1

Lana's stopwatch is the only one with a resolution to match 12.6 secs. The other two don't have sufficient resolution to distinguish between 12.6 and 12.7. Jane's would read 12.5 for 12.6 or 12.7 secs, and Keith's would read 13 secs, and his stopwatch would register as 13 seconds the winner's maximum time of 13.4 seconds, because at 13.5 or above Keith's would register 14 seconds. Jane's stopwatch would be the faulty one if the winner's time was 12.6, because it should have shown 12.6 instead of 12.7.