Increased profits for the April-June quarter were reported yesterday by a diverse group of companies based here - the Washington Post Co., Mack Co., Pargas and NUS Corp.

Washington Post Co. profits were $10.8 million in the second quarter ended July 3 compared with $7.7 million a year earlier, an increase of 40 per cent. With a smaller number of shares outstanding, per-share earnings were up 49 per cent to $1.28 from 86 cents. Revenues rose by 14 per cent to $113 million.

A statement by the communications firm said a nonrecurring insurance payment increased the recent quarter's profits by about $500,000 (6 cents a share). Martin Cohen, vice president for finance, said the insurance payment was related to a strike against The Post newspaper by the pressmen's union in late 1975 and early 1976.

The quarterly results brought Post Co. six-month profits to $15.8 million ($1.83 a share) compared with $11.5 million ($1.28) in the 1976 period, as revenues increased 16 per cent to $207.5 million.

In its report, the Post Co. said newspaper and magazine division revenues and pre-tax profits both increased during the recent three months; total advertising linage rose 10 per cent at The Post and 7.5 per cent at the Trenton, N.J., Times, while Newsweek ad revenues were up 14 per cent for the quarter.

Newspaper and magazine revenues each rose 16 per cent, but broadcasting revenues rose only 1 per cent, and there was a small decline in pre-tax profits of broadcasting for the quarter, the company said. The firm does not publish pre-tax figures for its various divisions on a quarterly basis.

Macke Co., a major vending and food service firm based in Cheverly, reported record profits of $1 million (35 cents a share) in the third fiscal quarter ended June 30, up 22 per cent from $844,000 (28 cents) for the same period last year. Sales rose 11 per cent to $52 million.

Higher profits for the April-June period - the ninth consecutive quarterly gain for Macke - brought nine-month earnings to $2.9 million (97 cents) compared with $2.5 million (84 cents); sales were up 10 per cent to $153 million.

Pargas, Inc., a Waldorf-based Distributor of liquefied petroleum gas, reported second-quarter profits of $761,446 (19 cents a share) vs. operating profits of $440,137 (13 cents) in the 1976 period. An extraordinary charge related to fighting a takeover last year reduced quarterly net income to $88.161. Sales rose to $28.7 million from $23 million.

Six-month profits were $4.2 million ($1.14) vs. $2.7 million (82 cents), not counting a special charge of $351.976. Revenues rose to $74.8 million from $59.5 million.

NUS Corp., an energy-environmental engineering and consulting firm based in Rockville, reported second-quarter profits of $252,000 (25 cents a share) compared with $100,000 (10 cents) a year earlier, as sales rose to $7.8 million from $6.1 million.