Eastman Kodak Co. said yesterday that higher sales volume of its cameras, film and other products helped boost profits 73 percent in the fourth quarter from a year earlier, despite the continuing strength of the American dollar, which has hurt overseas sales.

In another earnings report, People Express Airlines said it had "disappointing" profits in 1984 of $1.6 million -- down substantially from its 1983 profits of $10.4 million.

Kodak, based in Rochester, N.Y., said in a statement that profits rose to $204 million ($1.32 a share) in the fourth quarter, from $117 million (70 cents) in the fourth quarter of 1983. It said revenue rose 7 percent to $2.75 billion in the three months ended Dec. 31, from $2.57 billion a year earlier.

For the full year, Kodak said its profits rose 63 percent in 1984 to $923 million ($5.71), from $565 million ($3.41) in 1983.

Revenue rose 4 percent in 1984 to $10.6 billion, from $10.17 billion a year earlier, Kodak said, adding that higher volume, and not higher prices, was primarily responsible for the revenue increase.

Earnings from operations in 1984 were $1.55 billion, a 51 percent increase from 1983.

* People Express said it had a net loss in the fourth quarter of $8.9 million, versus a profit of $1.3 million in the last quarter of 1983.

The company attributed the decline to expansion costs and said it is still carrying huge numbers of passengers.

It said that its investors lost 18 cents a share for the year, with the majority of the decline coming in the fourth quarter, when the per-share loss was 53 cents.

"The disappointing results were due to the cumulative effects of the investments in 10 new cities since June of 1984," said People Expreess Chairman Donald Burr.