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Finding the Fourth Proportional to 1,261.57, 1,892.65 and 428.59

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Solution

The fourth proportional to 1,261.57, 1,892.65 and 428.59 is: 642.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,261.57 : 1,892.65 = 428.59 : x
  2. Step 2: Convert to fraction form
    1,261.57/1,892.65 = 428.59/x
  3. Step 3: Cross multiply
    1,261.57x = 1,892.65 × 428.59
  4. Step 4: Simplify right side
    1,261.57x = 811,170.86
  5. Step 5: Solve for x
    x = 811,170.86/1,261.57
  6. Step 6: Final answer
    x = 642.99

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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.