Keith as 11/12 hours to play, he has already played 1/4. which is the best estimate of the fractional part of an hour he has left to play. is greater than 0 but less than 1/4 is greater than 1/ but less than 1/2 is greater than 1/2 but less than 3/4 is greater than 3/4 but less than 1

The best estimate is greater than 1/2 but less than 3/4

Step-by-step explanation:

If you multiply 1/4 by 3/3 (which is also 1), you can change the denominator without changing the value.  So 1/4 is equal to 3/12.

Since keith has 11/12 hours to play, and he has already played 3/12 hours, subtract 3/12 from 11/12 to get 8/12 hours. This is how much time he has left to play.  

If you simplify 8/12 hours, you get 2/3 hours.

So the best estimate would be: greater than 1/2 but less than 3/4.