A Telektronics dental X-ray machine bears a label stating that the machine gives radiation dosages with a

Question:

A Telektronics dental X-ray machine bears a label stating that the machine gives radiation dosages with a mean of less than 5.00 mill roentgens (mR). Sample data consist of 36 randomly selected observations with a mean of 4.13 mR and a standard deviation of 1.91 mR. Using a 0.01 level of significance, test the claim stated on the label.