Question

By 1935 the proportion of women workers in the USSR’s workforce was what in every 5

Answer 1

Correct 2 is the right answer

Answer 2

Two in every five.

In the 1920s, the percentage of women in the USSR's workforce was about 1 in 4 -- remaining around 28% through most of that decade.  But those numbers would increase under the First and Second Five-Year Plans instituted by Joseph Stalin.  By 1935, the percentage of women employed in large-scale industry in the Soviet Union had grown to 40%  (representing two out of every five workers).  

For further information and detail, you might consult the book, The Position of Women in the USSR, by G.N. Serebrennikov (published 1937).