XML 71 R57.htm IDEA: XBRL DOCUMENT v3.21.2
Note K - Stock-based Compensation Plans - Options Valuation Assumptions (Details)
12 Months Ended
Apr. 30, 2021
Apr. 30, 2020
Apr. 30, 2019
Expected terms (Year) 5 years 6 months 5 years 6 months 5 years 6 months
Risk-free interest rate 0.36% 1.75% 2.79%
Volatility 50.00% 39.00% 36.00%
Dividend yield 0.00% 0.00% 0.00%