WASHINGTON — The Federal Reserve announced Wednesday another $10 billion cut in its monthly bond purchases in a statement that attributed the decision to “growing underlying strength in the broader economy.” The statement, published after a two-day meeting of the Fed’s policy-making committee, reflected the optimism of Fed officials that the economy is finally poised for faster growth after years of false starts and setbacks. It was the committee’s first unanimous decision since 2011. The Fed said it would expand its holdings of Treasury and mortgage-backed securities by $65 billion in February, down from $75 billion in January and $85...