I'm just curious. I already found a work-around.

testAry = ["5", "7", "9"]
p testAry
testAry = testAry.each { |n| n.to_i}
p testAry
------------------------------
The second output is still an array of strings.

--
Conscience is thoroughly well-bred and soon leaves off talking to those 
who do not wish to hear it.
-Samuel Butler, writer (1835-1902)