Time of the last bus to leave Taiyuan East Bus Station for Wutaishan.

I am rather worried that I may miss the last bus to Wataishan.
I got different answers the time of the last bus from the East Bus Station to leave for the mountain. Replies from two persons on eLong web said the last bus is at 3pm. To hire a vehicle for me is too expensive. May foreign friends who have taken the last bus to leave Taiyuan East Station to the mountain. please give a reply.