Letxdenote the time (in minutes) that it takes a fifth-grade student to read a certain passage. Suppose that the mean value and standard deviation ofxare=5minutesand=0.4minutes,respectively.

(a)

Ifx

is the sample mean time for a random sample ofn= 9 students,where is the sampling distribution ofx

centered, and how much does it spread out around the center (as described by its standard deviation)? (Round your answers to three decimal places.)

_x =___ minutes

_x=___ minutes

(b)

Repeat part (a) for a sample of size ofn=70and again for a sample of sizen= 100.(Round your answers to three decimal places.)

n=70

_x =____ minutes

_x= ____minutes

n= 100

_x =___ minutes

_x=____minutes