The arithmetic mean of all odd positive numbers less than 100 will be

49
49.5
50
50.5

The correct answer is (c) 50.0.

The arithmetic mean is the sum of a list of numbers divided by the number of numbers in the list. In this case, the list of numbers is all odd positive numbers less than 100. There are 49 numbers in this list, and their sum is 4900. Therefore, the arithmetic mean is 4900 / 49 = 50.0.

Option (a) is incorrect because 49.0 is not the arithmetic mean of all odd positive numbers less than 100.

Option (b) is incorrect because 49.5 is not the arithmetic mean of all odd positive numbers less than 100.

Option (d) is incorrect because 50.5 is not the arithmetic mean of all odd positive numbers less than 100.