Answer:
If we made the assumption that both countries had a per capita of $15,000 in 1960, country A, which entered an era of political stability, and applied liberal reforms, growing at a rate of 5%, would double its GDP per capita by 1975, reaching a GDP per capita of $31,183.92.
On the contrary, country B, which continued to grow by 1% per year, would only double its GDP per capita by 2030, reaching a figure of $30,101.45.
Therefore, it would take 55 years more for country B to double its per capita GDP level compared to country A.