Crude oil prices slumped Friday, bogged down by a mixed U.S. economic report and a stronger dollar, finishing the day down $2.87 to close at $77 a barrel.

Oil prices on the New York Mercantile Exchange gained 9 percent in October, aided by a dollar that weakened during the month and hopes of a resurgent global economic activity, MarketWatch.com reported.

The dollar picked up Friday as investors sought the safety of the near- zero-yield currency. The dollar index recently gained 0.5 percent to 76.317.

News that U.S. consumer spending fell 0.5 percent in September added to pressure in early trading, analysts said.

"(There) are still concerns over the strength of the recovery -- oil demand has been sluggish, illustrated by recent stock data, and oil producers have posted weak earnings reports as a result," Action Economics analysts told MarketWatch.

Gasoline prices fell 7 cents, or 3.5 percent, to $1.94 a gallon, while heating oil tumbled 7 cents to $1.98 a gallon.

Natural gas prices slipped 2 cents to $5.04 per million British thermal units.

At the pump, the national average price of unleaded gasoline rose Friday to $2.695 per gallon, up from Thursday's $2.691, AAA said.