Một khối lập phương có hai mặt sơn trắng hai mặt sơn đỏ hai mặt sơn xanh tung khối lập phương Tính xác suất để mặt trên cùng là sơn đỏ hoặc sơn trắng

The ages of personnel in the accounting department of a large company are normally distributed with a standard deviation of 7 years. there is a 0.02275 probability that the age of any randomly chosen person in the department is less than 22 and 0.15866 probabilty that the age of any randomly chosen person is greater than 43. what is the mean of this distribution?