Answer:
81 or higher
Step-by-step explanation:
Hello!
There will be 4 tests taken, as he already took 3 and is going to take his fourth.
We can multiply 80 by 4 to get 320. The sum of all the tests should be equal to this number, in order for the average to be 80.
Let the unknown test score be x:
- 86 + 72 + 81 + x = 320
- 239 + x = 320
- x = 81
The fourth score has to be 81 or higher.
