Suppose the average puppy weighs 10 pounds. A sample of 10 puppies yields a sample mean of 13.2 pounds and a sample standard deviation of 2.78 pounds. Assume the population standard deviation is known to be 5.25. You want to test whether the sample mean differs from the population mean of 10 pounds at a 5 percent level of significance using a two-tailed test. State the critical value.