By Paul Carsten and Matthew Miller BEIJING (Reuters) – Lenovo Group, the Chinese technology company that earns about 80 percent of its revenue from personal computers, is betting it can also be a challenger to Samsung Electronics Co Ltd and Apple Inc in the smartphone market. On Wednesday, Lenovo said it would buy Google Incs Motorola Mobility handset unit for $2.91 billion in the fourth-largest U.S. acquisition by a Chinese or Hong Kong company ever. We are not only the number one PC company in the world but with this agreement we will become a much stronger number three smartphone company, said Wong Waiming, Lenovos chief financial officer, on a conference call on Thursday. The stock fell 8.2 percent on concerns Lenovo might have overpaid for a loss-making business and would dilute the value of shares by issuing new ones to help pay for the purchases.