Convert each rate, Round to the nearest tenth if necessary (Please can someone help me with theses last questions)

19, 62 mi/h =ft/sec
20.40 m/s = ft/min
21. 100 ft/s =mi/h
22.2 qt/s = gal/min
23.8 qt/min =fl. oz./sec
24.40 m/s =km/h

Scores on a university exam are normally distributed with a mean of 78 and a standard deviation of 8. the professor teaching the class declares that a score of 70 or higher is required for a grade of at least “c.” using the 68-95-99.7 rule, what percentage of students failed to earn a grade of at least “c”?