You cannot find the mean and standard deviation of data design types. Because you convert the frequency into a classified variable, you can only count the percentage of people who choose multiple times a day, the percentage of people who choose once a day and the percentage of people who choose multiple times a week. . .

If you want to accurately calculate the average and standard deviation of frequency, you should not set this setting when designing the questionnaire, but directly let students estimate the number of times they go every day or week and directly let students fill in a certain number of times. With this setting, you can calculate the standard deviation of the average.