Often GMAT questions include unstated constraints, and there is an unstated constraint in this question. Since radios and clocks are sold as whole units, the unstated constraint in this question is that the number of clocks or of radios will be an integer.

Since Statement 1 says that the number of radios is greater than 28, and the number of radios has to be an integer, the minimum number of radios is 29. So, there could any number of radios from 29 to 44 in inventory.

So Statement 1 is insufficient.

Statement 2 gives us a maximum number of radios. Since the number of radios is less than twice the number of clocks, the number of radios is any integer less than 2/3 x 44.

So Statement 2 is insufficient.

Combining the information provided in the question, the information provided by the statements and the unstated constraint that radios and clocks must be counted in integer increments, we can calculate the following.

The minimum number of radios is 29, from Statement 1.

The maximum number of radios is less than 2/3 x 44, which is a little less than 2/3 x 45 which is 30. We know that the radios and clocks are counted in integer increments. So if the number of radios is less than 30, and has to be at least 29, there is only one number that works, 29.

We can check our work. 29 + 15 = 44. 29 is less than 2 x 15.

So the correct answer is C.

Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.

Q. A retailer sells only radios and clocks. If she currently has 44 total items in inventory, how many of them are radios?

I. The retailer has more than 28 radios in inventory.
II. The retailer has less than twice as many radios as clocks in inventory.

There are 2 variables (radios' number; r and clocks' number;c) and one equation (r+c=44). There are 2 more equations given by the conditions, so there is high chance (D) will be the answer,
For condition 1, r>28 and this is insufficient, as we do not get an unique value ofr r
For condition 2, r<2c and r<2(44-r), r<88-2r, 3r<88, r<88/3=29.33333...we also do not get the unique value of r, so this is insufficient
If we look at the conditions together,
28<r<29.33333..., and r=29. This issufficient and the answer becomes (C).

For cases where we need 1 more equation, such as original conditions with "1 variable", or "2 variables and 1 equation", or "3 variables and 2 equations", we have 1 equation each in both 1) and 2). Therefore, there is 59 % chance that D is the answer, while A or B has 38% chance and C or E has 3% chance. Since D is most likely to be the answer using 1) and 2) separately according to DS definition. Obviously there may be cases where the answer is A, B, C or E.

S1:: She could have 29 radios and 15 clocks or 30 radios and 14 clocks; NOT SUFFICIENT

S2:: She could have 29 radios and 15 clocks or 28 radios and 16 clocks; NOT SUFFICIENT.

Together, we have

r > 28

and

2c > r

So 2c > 28, or c > 14.

Since r > 28, c > 14, and r + c = 44, we must have r = 29 and c = 15. (If we make either variable larger, we'll be over 44.)