posted by UPD .
Information given:the distribution of male head circumference (HC) is normal with a mean of 56cm and a standard deviation of 1.8cm
-the prob that HC of a random chosen man is larger than 57.8cm is?
z=(57.8-56)=1.8--->.9641 i got it wrong?
what is is the sampling distrubution of the avg HC of 9 random selected men?
Third: the prob that the average HC of 9 random selected men is larger then 57.8cm is?