Home / 1,286.58-1,929.72-420.90

Finding the Fourth Proportional to 1,286.58, 1,929.72 and 420.90

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Solution

The fourth proportional to 1,286.58, 1,929.72 and 420.90 is: 631.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,286.58 : 1,929.72 = 420.90 : x
  2. Step 2: Convert to fraction form
    1,286.58/1,929.72 = 420.90/x
  3. Step 3: Cross multiply
    1,286.58x = 1,929.72 × 420.90
  4. Step 4: Simplify right side
    1,286.58x = 812,213.49
  5. Step 5: Solve for x
    x = 812,213.49/1,286.58
  6. Step 6: Final answer
    x = 631.29

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.