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Finding the Fourth Proportional to 1,285.89, 1,928.76 and 420.21

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Solution

The fourth proportional to 1,285.89, 1,928.76 and 420.21 is: 630.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,285.89 : 1,928.76 = 420.21 : x
  2. Step 2: Convert to fraction form
    1,285.89/1,928.76 = 420.21/x
  3. Step 3: Cross multiply
    1,285.89x = 1,928.76 × 420.21
  4. Step 4: Simplify right side
    1,285.89x = 810,484.24
  5. Step 5: Solve for x
    x = 810,484.24/1,285.89
  6. Step 6: Final answer
    x = 630.29

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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.