#
#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 = 20
SumX2 = 169
SXX = 90 
b0 = 6
s2 = 25     # 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( b0 - t * sqrt( s2 * SumX2 / ( n * SXX ) ) ) 
print( b0 + t * sqrt( s2 * SumX2 / ( n * SXX ) ) )