Write 58° 12′ in decimal degrees.

Correct answer: 58.2°

Direct answer: C, 58.2°. Degrees and minutes use a base-60 relationship, not a base-100 relationship. One degree equals 60 minutes, so the 12 minutes must first be converted into a fraction of a degree: 12′ = 12/60° = 0.2°. Add this fractional part to the whole-degree part: 58° + 0.2° = 58.2°. Therefore C is correct. A, 58.12°, incorrectly places the minute number after the decimal point as if 12 minutes meant 0.12 degree. B, 58.15°, would correspond to 9 minutes, not 12 minutes. D, 58.25°, would correspond to 15 minutes. Memory cue: for degrees and minutes, divide minutes by 60 before writing decimal notation.