#
#Epage 182
#
# Written by:
# -- 
# John L. Weatherwax                2009-04-21
# 
# email: wax@alum.mit.edu
# 
# Please send comments and especially bug reports to the
# above email address.
# 
#-----

n = 18
b1 = 3.1;
SXX = 144
s2 = 36     # this is an estimate of the common variance (the same for all x's)

ci = 0.95
alpha = 1 - ci

t = qt( 1 - alpha/2, n-2 )

print( b1 - t * sqrt( s2 / SXX ) ) 
print( b1 + t * sqrt( s2 / SXX ) )