Money market mutual fund assets rose $1.93 billion in the latest week to $391.84 billion, the Investment Company Institute reported.

Yields on 52-week Treasury bills fell to the lowest level since January. The average yield was 7.34 percent, down from 7.52 percent at the last auction on June 28. ACQUISITIONS

Westinghouse Electric said it has agreed to buy Knoll International for stock, making the electric company one of the world's three largest makers of office furniture. Specific terms were not disclosed. COMPANIES

Burger King, in cooperation with the French restaurant and hotel company Elitair, announced plans to open the first two fast-food restaurants at rest stops along French highways.

Quality International of Silver Spring said it is changing its name to Choice Hotels International. The company, a subsidiary of Manor Care Inc., franchises hotels and motels under the Clarion Hotels, and the Quality, Comfort, Rodeway and Sleep inns names.

Phoenix International, the diet-cookie maker forced by the FDA to recall its products earlier this year because of mislabeling, said it had donated $3.8 million worth of the cookies to a Chicago charity, Second Harvest, with FDA permission.

Shenandoah Fibers has scrapped plans to manufacture polypropelene at the closed Avtex Fibers plant in Front Royal, Va. Avtex closed last year after its waste water discharge permit was revoked for PCB contamination of the Shenandoah River. CONTRACTS

Martin Marietta received a contract it valued at $300 million to design and develop a new jet engine thrust reverser for Pratt & Whitney.

General Motors received a $65.8 million Navy contract for aircraft turbine engines. EARNINGS

Boeing reported its second-quarter earnings increased 99 percent compared with the year-ago period.

Compaq Computer reported second-quarter earnings increased 24 percent.

Delta Airline said its earnings for the three months ended June 30 fell to $74.1 million, from $190.8 million a year earlier.

Goodyear reported it lost $9.4 million in the second quarter, compared with a profit of $27.1 million a year ago.

United Airlines's parent, UAL Corp., reported a 5 percent gain in second-quarter profits.

Whirlpool said its second-quarter profit tumbled 26 percent.

Walt Disney Co. said its third-quarter earnings were up 23 percent. PEOPLE

O. Gene Gabbard was named chief financial officer at MCI. The appointment is contingent on completion of MCI's proposed acquisition of Telecom USA, an Atlanta-based long-distance phone company of which Gabbard is chairman.

Harold Simmons denied he is selling any of his holdings in Lockheed. Rumors that Simmons was dumping his 12 million shares contributed to a Wednesday sell-off of Lockheed stock, causing it to fall $2.75 to $26.37 1/2.

Robert A. Schoellhorn, former chairman of Abbott Laboratories, and the company reached a settlement under which pending litigation between the company and the ousted official will be dropped. Details of the agreement were not released.