Answer:
2%
Step-by-step explanation:
Original mass of water in glass = 10 ounces
amount that evaporates each day = 0.01 ounce
number of days = 20 days
Total amount that evaporated = 0.01 x 20 = 0.2 ounce
percentage of water that evaporated during this period = 0.2/10 x 100
= 2%
Hence, the percentage of the original amount of water evaporated during this period is 2%