How does plaque affect pressure in an artery?

[needhelpfast]

Homework Statement

Blood is a viscous fluid. If due to plaque, the cross-sectional area of an artery is reduced by a factor 4 over a segment with a length of 1.5 cm, approximately by what factor would the pressure difference between both ends of this segment need to be increased in order to maintain the same flow?

Homework Equations

P=pgh

The Attempt at a Solution

Doesn't only height matter and not the cross-sectional area? Any help is greatly appreciated!

 

[needhelpfast]

nevermind, got it!