What was going on when I was born?

Mexico announced today that it would raise its oil prices early next month and warned that buyers unwilling to pay the new price might permanently forfeit Mexico as an energy source. The announcement came just two weeks after Mexico lowered its oil prices $4 a barrel, becoming the first major oil exporter to reduce its official price in the face of the current glut on world oil markets. Since then, other oil producers, among them Ecuador, Britain and Norway, have lowered the export prices of their crude oil, and the price of oil on spot markets has dropped sharply. Mexico's announcement today did not indicate whether the full decrease of $4 a barrel would be reinstated, although this was the implication.The decision went in the face of the downward trend in world oil prices, brought on by the world oversupply of oil and declining demand.

An article on the World Bank in The Times Monday incorrectly identified Robert D. Muldoon. Mr. Muldoon is the Prime Minister of New Zealand.

International The sale of American weapons to China has been approved in principle, Secretary of State Alexander M. Haig Jr. announced at the end of a three-day visit to Peking. He told reporters that his talks with Chinese leaders had been ''unusually significant and successful'' and seemed to foreshadow ''a major expansion of Sino-American friendship and cooperation.'' (Page A1, Col. 6.) Israel apparently violated its accord with the United States on the use of American-made weapons when it bombed an Iraqi nuclear reactor on June 6, President Reagan said. But he also told a news conference that Israel ''might have sincerely believed'' that the action was defensive. (A1:5.)

IRANIANS SCHEDULE DEBATE TODAY OVER IMPEACHMENT OF BANI-SADR TEHERAN, Iran, June 16 (By Reuters) - Parliament decided today to begin impeachment proceedings against President Abolhassan Bani-Sadr tomorrow. The debate, which is expected to take three or four days, was scheduled as eight of the President's staff members were arrested and several others were expelled from his offices. Guards at the gates said only two women were left inside. There was no word on the whereabouts of Mr. Bani-Sadr, who has not been seen in public since shortly after Ayatollah Ruhollah Khomeini removed him Wednesday as Commander in Chief of the armed forces.

President Reagan said today that Israel appeared to have violated its weapons agreement with the United States when it bombed an Iraqi nuclear reactor 10 days ago, but that the Israelis ''might have sincerely believed'' their action was defensive in nature. At his news conference this afternoon, the President went further than any Administration official has before in suggesting that Israel had abused an agreement prohibiting its use of American-made military equipment for offensive military actions. Previously, officials had said only that Israel may have violated the agreement and that the matter was being reviewed. However, Mr. Reagan went on to endorse at least some of Israel's justifications for the raid, saying: ''I do think that one has to recognize that Israel had reason for concern in view of the past history of Iraq, which has never signed a cease-fire or recognized Israel as a nation, has never joined in any peace effort for that. So in other words it does not even recognize the existence of Israel as a country.''

Namibia council finds whites' grip remains strong A2 Police in Soweto break up me- morial meeting in church A3 Africans struggling to bring unity to O.A.U. A3 Reagan Administration favors a ban on whaling A4 Around the World A5 Saudis call mission "futile,"but Habib presses on A9 New Polish party people emerg- ing in elections to congress A10 Marcos, virtually unopposed, wins by a huge majority A12 U.S. envoy stresses commitment to Salvadoran jnta A13 Italy to investigate civil servants in Masonic scandal A14 Census enlivens quest for inde- pendent Quebec A15 Government/Politics Head of drug enforcement agency to leave office next month A18 Weicker uses oratory in effort to block a ban on busing A22 Reagan favors California gun laws rated as mixed success A28 Agriculture aide expected to end Human Nutrition Center A29 Engineer on M.T.A. panel sees Flxible buses back in July B2 Carey and Koch agree to seek cut in taxes on commercial banks B3 Koch budget proposals are facing opposition B3 McCann victor in Jersey City mayoralty runoff B6 General Survey finds some black support for lower minimum wage A18 Mine owners and union announce a tentative agreement A18 Around the Nation A20 Michigander lands new job and plans move to Texas A20 Jersey Transit plans to buy 117 high capacity buses B2 Living Section Food When it's hot, eat cool: Food for summer nights C1 Ices, etc., by an addict C1 Wine Talk: European prices are falling C1 Soups: Summer refresher courses C3 Pick your own berries at many farms in area C4 The short sweet season for green herring C16 Living Women seek out their history C1 Metropolitan Diary C2 Kitchen Equipment C2 60-Minute Gourmet C3 Best Buys C8 Discoveries C9 Personal Health C12 Nutritional requirements of the elderly C12 NASA tests "space suit" for plants C18 Cooks from upstairs at work downstairs C20 Health/Science Four cancer researchers named for General Motors awards B5 Arts/Entertainment "Gaijin," film about Japanese settling near Sao Paulo C23 A new musical, "El Bravo" C23 Jones and Plummer to star in "Othello" at Stratford, Conn C23 Poplife C25 San Francisco Opera gives pre- miere of Reimann's "Lear" C28 Turkish State Folk DanceEnsem- ble makes debut C28 Royal Ballet's "Sleeping Beauty" has a royal history C28 Masur conducts Philharmonic in spring series concert C28 Javits's autobiography is re- viewed C29 Romanos appointed Bantam Books publisher C30 "American Odyssey" on Channel 13 traces a cross-country trip C31 Obituaries John S. Knight, founded newspa- per publishing empire B5 Sports Steinbrenner, 2 other owners ap- pear to seek bigger role in talks B7 Watson feels time is right to win his first U.S. Open B7 Women protest Wimbledon seed- ings B7 Family ties strong for Otis Bird- song B7 Red Smith on boxing's Danish connection B8 Miss Mandlikova upset by Kim Sands in tennis B8 Features/Notes About New York B1 Notes on People C30 News Analysis Drew Middleton assesses the Rapid Deployment Force A8 Hedrick Smith discusses Reagan news conference A27 Sheila Rule discusses New York City's foster-care system B4 Editorials/Letters/Op-Ed Editorials A30 Too big for antitrust The professional Hard hat outlaws John P. MacKenzie: juries Letters A30 James Reston: Reagan's "fad- ing" Russians A31 Russell Baker: for the good of the game A31 David Ives: in praise of depres- sion A31 Edward Friedman: China and fragility A31

The Chicago Cubs, one of major league baseball's least successful franchises on the field in recent years, were sold yesterday for $20.5 million by William Wrigley to the Tribune Company, parent of The Chicago Tribune and The Daily News in New York. In announcing an agreement for the transfer of his 81 percent ownership and all remaining 1,900 shares in baseball's only publicly owned corporation, Mr. Wrigley, a Chicago chewing gum manufacturer, ended a family association with the National League team that began when his grandfather became a minority shareholder in 1916. That family tie, which was strengthened when the grandfather acquired a majority interest in 1921, was the oldest in major league baseball. The sale of the Cubs, which includes Wrigley Field and all the team's debts, was the second involving a Chicago baseball franchise this year. Last January a Chicago-based group purchased the White Sox for $20 million.

''We didn't live on the wrong side of the railroad tracks, but we lived so close to them we could hear the whistle real loud.'' - President Reagan. (A27:2.)

The venture capital business is booming, but Paul M. Wythes, a partner in Sutter Hill Ventures of California, is not all that happy about it. Venture capitalists, he says, are paying a lot more to invest in young companies and are being pressed to make quick decisions in order not to miss an opportunity. ''They're writing a check a lot faster,'' added Mr. Wythes, explaining that start-up companies were now able to pit investment firms such as his against one another. The underlying reason for these changes in the venture capital business, Mr. Wythes and others say, is that there is more money around than there are opportunities for investment. Shift in Initiative Found ''Now there are so many people out there with capital to invest that the initiative seems to have gone from the entrepreneur looking for money to the money looking for entrepreneurs,'' said W.J. Sanders 3d, the chairman of Advanced Micro Devices, a California semiconductor company.

Housing starts dropped 14 percent in May, to a seasonally adjusted rate of 1.15 million units, the Commerce Department reported. The level was the lowest since the 938,000 units begun last May during the bottom of last year's recession. Analysts said the slump would last as long as interest rates remained high. (Page D1.) The nation's industrial production rose 0.3 percent in May, the Federal Reserve Board reported. The slight increase was largely attributed to the building up of inventory by automobile makers. (D11.)

With a $150 million casino-hotel newly built and ready to open in Atlantic City, the Del E. Webb Corporation, the largest casino operator in the country, pulled out of New Jersey today under the cloud of a Federal indictment in Nevada charging criminal conspiracy. It was the first time a company had abandoned a New Jersey casino venture because of licensing problems. The Webb interest in the Claridge Hotel and the Hi-Ho Casino on the Boardwalk will be purchased by F. Francis D'Addario of Bridgeport, Conn., and others. A group headed by Mr. D'Addario is now a 50 percent partner with the Del Webb Corporation in the venture.

WHERE desserts are concerned, almost everyone I know is guilty of succumbing to one alluring vice or another. By ''vice'' I mean something sweet that is irresistible enough to offer sinful temptation, something that would arouse greed in an otherwise welltempered appetite; something to be indulged in without restraint, diets be damned. I am not a chocoholic, as most dessert lovers claim to be; I can take a bite of Sacher torte or a chocolate mousse with studied composure or leave it with casual abandon. Chocolate truffles, black or white, have an understandable appeal, but they do not induce in me anything that might approach gluttony. My weakness where desserts are concerned is only incidentally tempered to the current warm-weather season: I am addicted to wellmade ices, sherbets and ice creams. I am not one to race to the icebox for a midnight snack, I do not get the midnight munchies. But I am almost invariably tempted to visit the freezer after a meal at least once of an evening (and even twice if the craving gets too fierce) if I know there is homemade raspberry, grapefruit, strawberry or lemon ice waiting there. Or a fruit sherbet. And I am not above making that journey if the ice is not homemade, provided it is a good commercial product (the boysenberry sherbet of Haagen-Dazs falls into this category, to mention but one).