help me i dont understand why ux=3.5 and standard deviation =0,54???. what formulas are used ?? please do it clearly

39. A simulation was conducted using 10 fair six-sided dice, where the faces were numbered through 6, respectively. All 10 dice were rolled, and the average of the 10 numbers appearing faceup was recorded. The process was repeated 20 times. Which of the following best describes the distribution being simulated? (A) A sampling distribution of a sample mean with n= 10, y = 3.5, and o-0.54 (B) A sampling distribution of a sample mean with n = 10. My = 3.5, and o; = 1.71 (C) A sampling distribution of a sample mean with n = 20, My = 3.5, and oz - 0.38 (D) A sampling distribution of a sample proportion an = 10, H-a and 0= 0.118 (E) A sampling distribution of a sample proportion with n = 20, > and OM 0.083