31 ( they are : 4,6,9,10,12,14,15, 16,18,20,21,22,24,25,26,27, 28, 30, 32,33,34,35,36,38,40,42,44,45,46,48,49)
There are 15 prime numbers less than 50
positive square numbers less than 50 are 7 these are : 1,4,9,16,25,36,49.These are less than 50.
There are 15 composite numbers greater than 50 but less than 70
There are 15 prime numbers less than 50.
14 of them.
25
100
There are 25 even numbers less than 50 (2, 4, 6, ..., 48) and 25 odd numbers less than 50 (1, 3, 5, ..., 49). Therefore, the ratio of even numbers to odd numbers less than 50 is 25:25, which simplifies to 1:1.
4
4
There are 18.
There is only one and it is 2