GMAT Verbal Reasoning Practice Test 8

Trains T6 and T5 are not the in right order of arrival and should thus be diverted.
If you divert T6 first the resultant order will be: T1,T2,T3,T5,T4 and then T6 and if this is followed up by diverting T5 second, the resultant order will be: T1,T2, T3, T4,T6 and then T5. If T5 is diverted first the result will be: T1, T2, T3, T6, T4 and then T5. Followed by T6 being diverted second the result will be T1, T2, T3, T4. T5, and then T6.