When comparing seventeen twenty-eighths to one-half using mental math, what fraction is useful?

seventeen-halves

twenty-eight fifty-sixths

seventeen thirty-fourths

fourteen twenty-eighths

Question

When comparing seventeen twenty-eighths to one-half using mental math, what fraction is useful?

seventeen-halves

twenty-eight fifty-sixths

seventeen thirty-fourths

fourteen twenty-eighths

mathmale · Answer

You're comparing two fractions with different denominators.  Since the denominator of seventeen twenty-eighths is 28, multiply both numerator and denominator of one-half by 14, to obtain 14/28.  Now compare 17/28 to 14/28.  
Thus, the correct response is "fourteen twenty-eighths"