Question

In one day a baker used 1/3 of a pound of flour, then 1/4 of a pound then 5/12 of a pound of flour. How much flour was used that day? 7/12 pound7/19 pound1 pound5/12 pound

Answer 1

1 pound

1) Considering the given fractions we can write out the sum of these:

$\frac{1}{3}+\frac{1}{4}+\frac{5}{12}$

2) Since those fractions have different denominators, let's take the LCM (Least Common Multiple) of 3,4,12:

Notice that we prime factorize it, and now the common denominator will be 12. So we can write 12 on the denominator and divide by each denominator and multiply by each respective numerator. This way:

$\begin{gathered} \frac{1}{3}+\frac{1}{4}+\frac{5}{12}= \\ \frac{12\colon3\times1+12\colon4\times1+12\colon12\times5}{12}= \\ \frac{4+3+5}{12}= \\ \frac{12}{12}= \\ 1 \end{gathered}$

3) Hence, the amount of flour used was 1 pound.