LinkedIn Corp. has added a question-and-answer service to its business-oriented networking site, the latest Internet company to unveil this type of increasingly popular feature. LinkedIn Answers, now in preview mode, was be officially announced last month, but even before the launch members of this professional networking site posted almost 2,000 questions in the first four days, a spokeswoman for the company said. About 80 per cent of the posted questions have been responded to with an average of five answers. By adding a Q&A feature, LinkedIn joins others like Yahoo Inc. and Microsoft Corp., which let users of their respective search engines post questions and answers, tapping the collective knowledge of their user base. Members who provide an answer deemed as the best one to a specific question will receive an “expertise badge” on that topic, which will be added to their profiles, a good way for consultants and other service providers to promote their services on the site, the spokeswoman said. At LinkedIn, to which about 9 million professionals belong, the answers service will complement a menu of business networking features like job search, member-to-member messaging, professional recommendations and a contacts list. LinkedIn launched in 2003. Its investors include Sequoia Capital, Greylock Partners and Marc Andreessen.