Answer:
0.0266, 0.9997,0.7856
Step-by-step explanation:
Given that the IQs of university​ A's students can be described by a normal model with mean 140 and standard deviation 8 points. Also suppose that IQs of students from university B can be described by a normal model with mean 120 and standard deviation 11. Let x be the score by A students and Y the score of B.
A)
B) Since X and Y are independent we have
X-Y is Normal with mean = 140-120 =20 and
C) For a group of 3, average has std deviation =