The fastest growing plant on record is a hesperoyucca whipplei that grew 3.7 m in 14 days what was its growth rate inmicrometers per secon

just watch the units:

3.7m/14days * 10^6µm/m * 1day/86400s
= (3.7*10^6)/(14*86400)
= 30.59 µm/s