USB analyst Maynard Um told clients today in a note that Apple sold 7.5 million iPhones in the first three months of 2010, according to a recent Q-Series survey.

The study also found that Apple leads the smartphone industry in both mindshare and retention rate. Fifty-six percent of respondents in the Q-Series survey think Apple is the best smartphone manufacturer. According to “AppleInsider” (http://www.appleinsider.com) the implied retention rate among a sample of 310 users is 95 percent. As Um notes, that’s well beyond anything else seen ever in the industry.

What’s more, 90% of iPhone owners think that Apple is the best handset maker on the market, the analyst adds. When it comes to the iPad, Um is forecasting that Apple will ship 2.1 million in its 2010 fiscal year and 4.6 million in fiscal year 2011.