If a person can swim 100yd in 1 minute then how fast can they swim 100m OR if a person can swim 100m in 1 minute then how long will it take them to swim 100yd?

if you swim 100m in 60 secs then you should be able to swim 100yd(=91.44m) in 60*91.44/100=54-55sec

If you swim 100yd in 1 minute you probably will be able to swim 100m in 91.44/60*100=65-66 secs. Since 100m is longer than 100yd this time will be correct provided you can swim the last 10 meters at the same speed as you swim the 100yds.