Question

In building a house, carpenters use nails from a large box. The box is suspended from a spring twice during the day to measure the usage of nails. At the beginning of the day, the spring stretches 50 cm. At the end of the day, the spring stretches 30 cm. What fraction or percentage of the nails have been used?

a) 40%
b) 50%
c) 60%
d) 75%

Answer 1

To find the fraction or percentage of nails used, we need to use proportional reasoning. The amount of nails used is directly proportional to the amount the spring stretches.

Step-by-step explanation:

To find the fraction or percentage of nails used, we can use the concept of proportional reasoning. We can see that the spring stretches from 50 cm to 30 cm, which is a difference of 20 cm. Since the amount of nails used is directly proportional to the amount the spring stretches, we can set up the following proportion: \\ \frac{{\text{{amount of nails used}}}}{{\text{{total amount of nails}}}} = \frac{{\text{{spring stretch}}}}{{\text{{initial spring stretch}}}} \\ \frac{{\text{{amount of nails used}}}}{1} = \frac{{20 \, \text{{cm}}}}{50 \, \text{{cm}}} \\ \text{{amount of nails used}} = \frac{{20 \, \text{{cm}}}}{{50 \, \text{{cm}}}} \\ \text{{amount of nails used}} = \frac{2}{5}