Answer: 3 tons of glass in a day.
Step-by-step explanation: If a plant processes 1/8 ton of glass every 4 hours, it processes 1 ton of glass every 8 hours because 8 x (1/8) = 1.
Since there are 24 hours in a day, the plant will process 1 ton of glass every 8 hours for a total of 24/8 = 3 times in a day.
Therefore, the plant will manufacture 3 tons of glass in a day.