DRUGS RISKS, REWARDS HIGH FOR WASHINGTON, D.C. SELLERS

----WASHINGTON A typical young, poorly educated black man selling drugs on the streets of the nation's capital can count on earning $2,000 a month tax free, the Rand Corporation said Tuesday.

Not enough for a ''Mercedes or great fortunes,'' but more than four times as much an hour as drug dealers can expect to make from legitimate jobs.

Researchers based their conclusions on information supplied by the city government about the 24,000 people arrested for selling or possessing drugs from 1985 through 1987; interviews with 186 men aged 18 to 40 who said they had been involved with drugs and were on probation during that time; and a survey of 387 boys aged 15 to 18.

The report estimated that, in 1987 alone, an estimated 24,000 city residents were selling drugs on the street. For the three in eight dealing daily, the median monthly earnings were $2,000, or $30 an hour, after expenses.

That compares to the $7 an hour from the legitimate jobs that 75 percent of the probationers reported holding.

The study found that dealers active at least two days a week face a 22 percent chance of going to prison, a 7 percent chance of severe injury and a 1.4 percent chance of being killed a fatality rate 100 times that of the general work force.

Given those risks, ''long periods of steady earnings are unlikely to be common,'' the report said.

''We came to this study from an employment perspective,'' said Karen Hastie Williams, chairwoman of the Committee on Strategies to Reduce Chronic Poverty, one of the groups that commissioned the study.

''We hoped to identify employment and training strategies to convince drug dealers to end their involvement in the underground economy and join the legitimate work force.''

But, conceded economist Peter Reuter, ''Even creation of considerably higher paying legitimate jobs probably wouldn't get us very far. Dealers would still have smaller total incomes than they can earn now by supplementing their regular wages with drug selling. Also, many have expensive drug habits.''

The estimated median income of street-level drug dealers was higher than the average $12,898 retail-trade workers made in 1987-88, according to the city government.

Construction workers made $24,879, on average, while service-industry workers made $26,545. The average annual salary for all private-sector workers was $25,857; government employees made $32,118.

Reuter, the report's principal author, said in an interview that, while most street-level sales were by blacks, the availability of drugs in Washington affects not just the city's predominantly black population.