9/8 feet per hour fast is Kelly's knitting speed Step-by-step explanation: Unit rate defined as the rates are expressed as a quantity 1 such as 4 meter per seconds or 4 miles per hour. As per the statement: Kelly is knitting a scarf for her brother. it took her 1/3 hour to knit 3/8 foot of the scarf. She took /3 hour to knit 3/8 foot of the scarf.