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Finding the Fourth Proportional to 1,243.64, 1,864.71 and 421.90

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Solution

The fourth proportional to 1,243.64, 1,864.71 and 421.90 is: 632.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,243.64 : 1,864.71 = 421.90 : x
  2. Step 2: Convert to fraction form
    1,243.64/1,864.71 = 421.90/x
  3. Step 3: Cross multiply
    1,243.64x = 1,864.71 × 421.90
  4. Step 4: Simplify right side
    1,243.64x = 786,711.83
  5. Step 5: Solve for x
    x = 786,711.83/1,243.64
  6. Step 6: Final answer
    x = 632.59

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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.