Temp = [100,75,50,25,0,-25,-50,-65,-75,-85,-100,-125,-150,-175];
Impact_Energy = [89.3,88.6,87.6,85.4,82.9,78.9,73.1,66,59.3,47.9,34.3,29.3,27.1,25];
% Part B
Avg = (89.3+25)/2; % This average is measured in Joules
plot(Temp,Impact_Energy,'r*')
title('Impact Energy V. Temperature')
xlabel('Temperature, measured in C')
ylabel('Impact Energy, measured in J')
set(gca, 'XLim', [-180, 200], 'XTick', -180:10:200,'XTickLabel', -180:10:200,'Fontsize',10);
hold on
scatter(Temp,Impact_Energy,'X')
line(Temp,Impact_Energy)
% hold off
% DRaw line at x = 70
x = 70 ;
y = interp1(Temp,Impact_Energy,x) ;
plot([x,x],[y,0],'--r')
plot([x,-180],[y,y],'--r')
YOu may follow the same for other line.