Why adding HBr to 2,4-hexadiene provides direct addition and conjugate addition products, while addition of HBr to 1,5-hexadiene provides only direct addition product?

a pan containing water is placed in a positio n where it is exposed to a 10 mile per hour wind. the pan contains a uniform depth of 1.27 cm of water, is quite wide, and has a length of 2.44 m in the wind direction. the water in the pan is at a constant temperature of 15.5 °c.

it is reliable if two scientists recorded it