Question

as a result of economic growth during the 1950s, the percentage of americans who were in the middle class
increased slightly.
increased greatly.
decreased slightly
decreased greatly.

Explanation:

The 1950s U.S. economic boom (post-WWII prosperity, suburbanization, rising wages, new consumer economy) led to a massive expansion of the middle class, with a large share of Americans moving into middle-income households.

Answer:

increased greatly.