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Stock-Based Compensation (Tables)
9 Months Ended
Feb. 29, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]  
Fair Value of Options Granted Estimated at Date of Grant Using Weighted Average Assumptions

The fair value of the options granted during the nine months ended February 29, 2016 were estimated at the date of grant using the following weighted average assumptions:

 

Volatility

     55.8

Risk-free interest rate

     2.22

Expected option life in years

     9.72   

Dividend yield

     0