How many companies had an april 2013 cumulative ranking of 3?
create table table_23950611_2 (market_cap_march_15__mil_usd__ varchar, april_2013_cum_rank varchar, PRIMARY KEY (market_cap_march_15__mil_usd__))
select count(market_cap_march_15__mil_usd__) from table_23950611_2 where april_2013_cum_rank = 3