College

Which of the following proportions is false?

A. [tex]\frac{25}{45}=\frac{50}{90}[/tex]
B. [tex]\frac{20}{50}=\frac{40}{100}[/tex]
C. [tex]\frac{18}{48}=\frac{30}{50}[/tex]
D. [tex]\frac{12}{15}=\frac{20}{25}[/tex]

Answer :

To figure out which proportion is false, we need to check if the two fractions in each pair are equivalent. A quick way to do this is by cross-multiplying the fractions and comparing the results for equality. Let's evaluate each pair step by step:

1. First Pair: [tex]\(\frac{25}{45} = \frac{50}{90}\)[/tex]

- Cross-multiply: [tex]\(25 \times 90 = 2250\)[/tex] and [tex]\(45 \times 50 = 2250\)[/tex]
- The results are equal, so this proportion is true.

2. Second Pair: [tex]\(\frac{20}{50} = \frac{40}{100}\)[/tex]

- Cross-multiply: [tex]\(20 \times 100 = 2000\)[/tex] and [tex]\(50 \times 40 = 2000\)[/tex]
- The results are equal, so this proportion is true.

3. Third Pair: [tex]\(\frac{18}{48} = \frac{30}{50}\)[/tex]

- Cross-multiply: [tex]\(18 \times 50 = 900\)[/tex] and [tex]\(48 \times 30 = 1440\)[/tex]
- The results are not equal, so this proportion is false.

4. Fourth Pair: [tex]\(\frac{12}{15} = \frac{20}{25}\)[/tex]

- Cross-multiply: [tex]\(12 \times 25 = 300\)[/tex] and [tex]\(15 \times 20 = 300\)[/tex]
- The results are equal, so this proportion is true.

After checking each pair, we find that the third proportion, [tex]\(\frac{18}{48} = \frac{30}{50}\)[/tex], is false. The cross-multiplication results are not equal, indicating that these fractions are not equivalent.