Addressing a political rally recently, Prime Minister Robert Mugabe asked why blacks were resorting to strikes now that Africans had finally won control of the nation that whites had ruled for three generations as Rhodesia.

The answer came back swiftly from the crowd: "Money! Money! Money!"

The chanting was not angry -- the 35,000 at the rally were Mugabe supporters. They were stating a fact of life in one-year-old Zimbabwe: most blacks don't have much money; most whites do.

That enduring economic reality a year after blacks achieved political control here leaves Mugabe stranded on a tightrope in running this key southern African nation.He must move fast enough to meet the aspirations of 7 million blacks and forestall a rebellion. Yet the transformation has to be slow enough so the fewer than 200,000 whites, the driving force behind the nation's successful economy and agriculture, do not flee.

Mugabe's performance could have far-reaching significance for the West, particularly for the Reagan administration, which is concerned about Soviet involvement in mineral-rich southern Africa.

In a message to the nation in honor of its Independence Day, celebrated on April 18, President Reagan said Zimbabwe plays "a pivotal role in southern Africa" and praised the "moderate course" followed by the government.

Little more than a year ago such a statement would have been extraordinary.

For 15 years the country was the problem child of African diplomacy as Britain tried to bring black-majority rule to its breakaway colony of Rhodesia. Africans finally took up arms and the bitter seven-year guerrilla war made it even less likely that the strife-torn country could stand as a model for a flourishing multiracial society.

Yet today, after the first year of black rule, Zimbabwe has become a rare African success story, despite some setbacks.

Although beset with problems that are an outgrowth of the brutal independence fight, Zimbabwe has by far the strongest economy of any black nation in the region. Fifteen years of international sanctions have made the country more self-sufficient.

Independence last year led directly to the formation of a nine-nation grouping to promote stability and cooperation in the region and end the economic stranglehold white-ruled South Africa has on most of the countries.

Such stability could reduce the possibility of Soviet involvement in the continent's last, but most important liberation struggle -- for majority rule in South Africa. Failure of Zimbabwe and instability in the area, on the other hand, could invite an increased Soviet role.

A successful, multiracial Zimbabwe can also stand as an example to South Africa of an alternative to racial confrontation.

This four-part report will examine the transformation Mugabe has wrought and the challenges for the future now that he has put his imprint on the government. It will also assess the future of the whites and look at some of the key problem areas -- violence in the aftermath of the war and the needs of the peasants for arable land.

One of the biggest changes is psychological, a result of the war ending. Except in areas where the former guerrillas are balking at being disarmed, fear about security has greatly diminished.

No longer are people subject to search on entering buildings. Civilians have stopped carrying weapons openly on the streets of Salisbury. A number of farmers have removed their fortress-like defenses. Pilots land airliners without using evasive maneuvers for fear of being rocketed.

The perception of Mugabe outside Africa also has undergone a transformation. From a wartime leader using the violent rhetoric of a liberation struggle, he has become a peacetime prime minister urging reconciliation among the enemies of yesterday to work together for a better tomorrow.

His professed Marxism has been readily refined to meet the needs of the capitalist economy he inherited. To Mugabe, Marxism means ending exploitation of blacks. Most West European social democrats would be at home with his policies.

"One year of independence has shown that nationalism is more important than ideology," said Roger Riddell, who was close to Mugabe during the war and now heads a commission recommending changes to help the poorest.

There are considerable differences among Africans on how fast the pace of change should be.

Two university-educated blacks, working as government land resettlement officers, complained bitterly. "Whites are using Mugabe's reconciliation policy to keep control," said one. Both felt the government should seize land for resettlement despite a constitutional prohibition.

A more generally held view among the rural poor, however, was reflected in the remark of Reuben Mutwira, a former refugee in Mozambique and now a provincial teacher.

"Change can't be made overnight," he said. "It will come bit by bit."

Probably one of the best things going for Mugabe is the amazing patience of most Africans.

"Conditions are a little bit better -- it is a beginning," said John Mazikama, who earns about $50 a week where he has worked for seven years. Since he is above the newly implemented minimum wage, he only got a raise of about $1.50 a week.

He is buying a small, two-room house in Salisbury's dreary all-black satellite city of Chitungwiza. To supplement their income, his wife sells groceries, such as sugar, coffee and corn meal, that Mazikama brings on the bus from Salisbury. They made about $15 a week profit.

Still, their income is far too small to afford a house large enough for their five children, who all live with their grandparents on a tribal trust land near the Mozambican border.

Mazikama said he thinks that if he works hard he can get rich "like the white man."

His sister Lillian, however, said, "I think the whites are rich because they make the African slave for them." Both are loyal supporters of Mugabe's party.

Economist Riddell predicted that sharp increases in the minimum wage and income taxes are likely later this year as part of the effort to narrow the gap between whites and blacks.

The gap is huge. According to Bernard Chidzero, minister of economic planning and development, average white income is 10 times that of urban blacks and 100 times that of the rural black population.

The government ordered a minimum wage last year that raised farm workers and domestics from as little as $8 a month, plus food and housing, to $47 a month. Urban workers have gone from a minimum of about $35 total to $133 in manufacturing and commercial enterprises. The average wage in those areas has doubled to more than $140 a month, according to Labor Minister Kumbirai Kangai.

One side effect of the raises has been a shortage of meat and dairy products caused by increased demand.

Mugabe has talked of raising the top minimum to about $200, the official property line. Some businessmen say this will simply add to the already large ranks of the unemployed.

Riddell, whose commission has investigated incomes, price and conditions of service, estimates that unemployment and underemployment in the country may range as high as 40 percent.

Although many employers complained before implementation of the minimum wage last year that it would cause unemployement, Riddell said there were few layoffs.

By Western standards, Zimbabweans enjoy a low income-tax rate.

The maximum rate on gross income is slightly more than 50 percent but after allowing for deductions, the maximum effective rate is 36 percent, according to Riddell.

There is no tax on unearned income and tax on companies averages only 25 percent. In 1977-78 the mining industry paid only $3.5 million in taxes on $115 million revenue, a rate of 3 percent.

Most of the mining industry, like some other areas of the economy, is controlled by South African interests, a fact that could place considerable constraint on the government.

Almost all of Zimbabwe's trade goes through South African ports, using the railways of the white-rule country.

Last month Pretoria gave one year's notice that it would end its preferential trade agreement with Salisbury.

The state of the economy is another factor that will limit the pace of change. A 10 percent real growth rate was achieved last year after several years of negative growth during the war, but inflationary pressure is growing.

The cost of living rose by about 10 percent in 1980 and is expected to increase by an estimated 15 percent this year.

Helping to fuel inflation is an $840 million deficit in an overall budget of $1.8 billion, mainly a result of government attempts to expand services.

Cabinet ministers point out that the government is trying to serve the entire country on a basis of equality rather than giving priority to the privileged white minority. This has resulted in major changes in social services, which are bound to have at least a temporary negative impact on the quality of such services as education and health care for whites.

School enrollment has more than doubled from 800,000 to 1,760,000. More than 2,000 schools closed by the war have been reopened.

The government has instituted free primary education. More important in the long run, it has opened the way for the first time for large numbers of Africans to attend seconday school. Students entering the first year of secondary school increased from 17,000 to 90,000. One result has been an acute shortage of teachers and overcrowed classes.

The major change in the health field is that hospital and clinical care is now free for anyone earning under about $235 a month, which covers the bulk of the African population.

The number of people treated has more than doubled, according to Simon Mazorodze, deputy minister of health. Whites often complain that free treatment has led to abuses and overcrowding of facilities.

Mazorodze acknowleges that there have been abuses but "the end result is that the number of people seriously ill, needing hospitalization must, of necessity, drop."

Changes in other areas will come more slowly, he admits.

The government intends to switch the emphasis from curative to preventive medicine and to bring health care to the rural areas where Mazorodze estimates there is only one doctor for every 200,000 persons.

Close to half the country's 700-plus doctors are concentrated in the two largest cities, Salisbury and Bulawayo. Only 10 percent of the health care budget in the past was spent in rural areas, according to Mazorodze, while Salisbury maintained excellent facilities.

First, however, there has been the matter of reopening almost 300 provincial clinics and hospitals destroyed or damaged during the war. With the help of $3.2 million in U.S. aid, most have been restored.

The government hopes to open 100 new rural outpatient clinics a year to be staffed by paramedics with three years of training. Some of the $2 billion in foreign assistance pledged to Zimbabwe last month is to be used.

One of the key challenges for the government is in the field of technical training, since the emigration of whites has caused acute shortages of personnel.

Concrete plans await the completion of a year-long manpower study that has just been started, but Frederick Shava, minister of manpower planning and development, made it clear in a recent speech that employers should start making changes or the government will.

He cited statistics showing that last year the intake into major apprenticeship training programs was still overwhelmingly white and called this "a highly unsatisfactory situation."

He rejected as "complete and utter nonsense" the argument ofter heard here that "Africans, because of their cultural background, are unable to cope with technolgical concepts."

"Government will obviously have to take a much more active role in the recruitment and selection of apprentices," he said. Shava added that the government "may have to recommend acceptable proportions to employers." Although the intention was not to use coercion, "stricter methods may have to be used to achieve the desired objective," he said.

Shava may have to carry out his threat. It seems that the government's own airline, Air Zimbabwe, has not gotten the message.

A 22-year-old white with a background in music and no technical training said he placed an "employment wanted" ad in Salisbury's daily newspaper two months ago and was quickly hired by the airline to do electroplating.

The employe, who asked that his name not be used, readily admitted to a reporter that the few black journeymen, all working for lower salaries, had better qualifications.

The foreman told the young man to apply directly to him at the workshop rather than the administration. That way, the foreman said, he could avoid hiring a kaffir, the southern African equivalent of saying "nigger".