At a swim meet, Dillon dives from a diving board and his position above the water is represented by the equation where represents the time in seconds and represents height in meters. Part A: Dillon was investigating the time it takes him to enter the water after making the jump from the diving board. He began solving the equation by completing the square and arrived at the following form.

(t+β)^2= 249/16

What is the value of β?

Part B: How much time does it take Dillon to enter the water after making the jump from the diving board? Round your answer to the nearest tenth.
(seconds)