you automatically have a 25% (1/4) of getting blue. the odds of you spinning is 60 times and landing on blue is 15/60.
Theoretical Prob= 15/60 (simplified to 1/4)
Ex Prob= the amount of times you spun it and it actually landed on blue. i would suggest making up a reasonable number. I would say 24. so the experimental prob would be 24/60 (simplified to 2/5)