Identify the correct statements:
I. Veins are bright red in colour and provided with wide lumen
II. Veins are non-valvular and blood flows in veins by jerks.
III. Arteries are provided with thick tunica media.
IV. Veins end in capillaries and arteries start with capillaries.
The percentage error in the measurement of mass and velocity are 3% and 4% respectively. The percentage error in the measurement of kinetic energy is:
If \( L, M, N \) are the midpoints of the sides PQ, QR, and RP of triangle \( \Delta PQR \), then \( \overline{QM} + \overline{LN} + \overline{ML} + \overline{RN} - \overline{MN} - \overline{QL} = \):