Answer: 60%
Step-by-step explanation:
Since, According to the question, Last quarter, we successfully completed an average of about 5 chemical analyses per day.
Therefore initially our average = 5 chemical analyses per day.
Again, From the question, This quarter, we have increased this average to about 8 per day.
Therefore New average =chemical analyses 8 per day
Thus, Percentage change in the average = (Initial average - New average)×100/ initial average
= 
= 
= 60 %
Therefore, Percentage change in the average=60 %