Answer:
If the whole world were to go by the same time zone there would have been economic, psychological, physical, and many other problems.
Step-by-step explanation:
The world is divided into 24 time zones, and this has been done with a good reason. The reason why this is the case is so that the local population has the time set properly in accordance with the day and night patterns, as well as to be able to function properly in accordance to the human's biorhythm and os that the economy can function properly. If this was not the case, but all world was going by the same timezone there would have been a lot of problems.
The most noticeable problems would have been in the mental and physical health of humans, which in turn would have also caused big economic problems. The majority of the world's population would have been active in periods that are not natural for humans, especially not being active throughout most of the night. This would have caused large scale mental problems, but also drop off in the physical performances. With these two things becoming widespread, the productivity of the humans would sharply decline, so there will be huge economic dropp off as well.