Based on the capital to labor ratio and the labor force growth rate, the growth rate of the Solow residual is 2.5%.
This is the part of the growth in real GDP that is not as a result of an increase in capital or labor. The capital remained at zero growth and the labor was growing at 1.5%.
The Solow residual growth rate will then be:
= Real GDP growth rate - Labor force growth
= 4% - 1.5%
= 2.5%
Find out more on the Solow model at https://brainly.com/question/15687941.