Is the strep virus getting harder or easier to heal? Pediatricians are interested in studying the average length of time patients with strep are runni

Is the strep virus getting harder or easier to heal? Pediatricians are interested in studying the average length of time patients with strep are running fever while on antibiotics. In previous years, the average length of time patients ran fever with strep while on antibiotics was 1.8 days. A random sample of forty-six recent patients with strep ran fever while on antibiotics for an average of 2.3 days with standard deviation 1.2. At the 5% significance level, can pediatricians conclude that the average amount of time patients with strep run fever while on antibiotics has changed? Assume the random variable has a normal distribution.