Question 904018
s = 51/sqrt(9) = 17
t(250) = (250-260)/17 = -.588
p-value =P(t< -.588 when df = 8) = tcdf(-100, -.588, 8) 
Recommend following references:
http://stattrek.com/online-calculator/t-distribution.aspx
for use of TI Calculator (Calculator a must)
http://www.youtube.com/watch?v=S81bgxKI-cI