Answer:
7/16 inches.
Explanation:
The next size smaller than 1/2 inch would be 1/2 minus 1/16 inch large.
The first step would be to make 1/2 have the same denominator as 1/16, by changing it to 8/16, an equivalent fraction.
8/16 - 1/16 is 7/16, so the wrench you should try next is 7/16 inches.