Question on Quant "Central Limit Theorem" standard, understand, reading, average

transferpricing

Could any of you help to explain for me?
I dont understand how they calculate the “overall average sample means and standard errors” of continous population: In reading 10 (line 4, page 485), how can they get the number of $49.92 (average sample means) and $2.80 (standard error)
many thanks

Dapper425

thanks, lzen5.

Andreas42

they havent stated the actual population /samples hence theres no way you can compute these values.They’ve got the values , calculated the x and sd and then simply stated these final values.