Using descriptive statistics, you have found out that it takes an average of 40 minutes to complete a mid-term examination in isds 361 a. however, you were surprised to see that the median completion time is 55 minutes. this observation means thata. exam completion time is positively skewedb. exam completion time is negatively skewedc. exam completion time resembles the normal distributiond. exam completion time is probably tri-modal