Research indicates that bicycle helmets save lives. A study reported in Public Health Reports (May June 1992) was intended to identify ways of encouraging helmet use in children. One of the variables measured was the children's perception of the risk involved in bicycling. A four-point scale was used, with scores ranging from 1 (no risk) to 4 (very high risk). A sample of 797 children in grades 4-6 yielded the following results on the perception of risk variable i = 3.39,5 = 80. Calculate a 90% confidence interval for the average perception of risk for all students in grade 4-6. What assumptions did you make to assure the validity of the confidence interval? b. If the population mean perception of risk exceeds 2.50, the researchers will conclude that students in these grades exhibit an awareness of the risk involved with bicycling Interpret the confidence interval constructed in part a in this context