Nov 2 (Reuters) - Berkshire Hathaway Inc, the conglomerate run by billionaire Warren Buffett, on Friday said its third-quarter profit rose as strength in the railroad and utility businesses, as well as investment gains, offset weaker results in the insurance units. Berkshire earned $3.92 billion, or $2,373 per Class A share, compared with $2.28 billion, or $1,380 per share, a year earlier. Book value, Buffett's preferred measure of the company's worth, rose to $111,718 per Class A share, up 11.9 percent since year end.