A Base on d₂

Difficulty: Medium · Topics: Probability, Probability, Combinations

All the triangles with vertices among the points on the parallel lines d 1 and d 2 are drawn.

graph "x":[-0.6,5.4],"y":[-0.7,2.3],"axes":false,"ink":true,"label":"Two parallel lines: d1 carries A, B, C and d2 carries D, E, F, G","items":["type":"line","from":[0,1.6],"to":[4.4,1.6],"type":"line","from":[0,0],"to":[4.4,0],"type":"label","at":[4.8,1.6],"text":"d₁","type":"label","at":[4.8,0],"text":"d₂","type":"point","at":[0.7,1.6],"label":"A","anchor":"n","type":"point","at":[1.7,1.6],"label":"B","anchor":"n","type":"point","at":[2.7,1.6],"label":"C","anchor":"n","type":"point","at":[0.7,0],"label":"D","anchor":"n","type":"point","at":[1.7,0],"label":"E","anchor":"n","type":"point","at":[2.7,0],"label":"F","anchor":"n","type":"point","at":[3.7,0],"label":"G","anchor":"n"]

One of them is chosen at random. What is the probability that its base (the side lying on one of the lines) is on d 2?