Answer:
5.7
Step-by-step explanation:
5.666666666 can be rounded to 5.7 because the first decimal place occurs immediately after the decimal point.
I.e. in the number 1.23456, the first decimal place value is 2.
Meaning when we round, we look at the second decimal place. Given that 5.666666666 has a second decimal place greater that 5, we can round to 5.7