Consider the given data.
x 2 4 6 7 10 11 14 17 20
y 4 5 6 5 8 8 6 9 12
a - find the least-squares fit. derive the least-squares fit of the following model:
y=a1x+e
that is, determine the slope that results in the least-squares fit for a straight line with a zero intercept for the given data. (round the final answer to four decimal places.)

Amixture of slurry and mud is to be pumped through a horizontal pipe of diameter 500 mm. the fluid behaves as a bingham plastic with a yield stress of 30 pa and viscosity 0.04 pa.s. describe the effects of the shear stress through a transverse section of the pipe by plotting the variation in shear stress and velocity profile: (i) just before the slurry starts to move (ii) as the slurry flows when the pressure gradient is double that in part (i)