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Finding the Fourth Proportional to 813.90, 1,121.88 and 666.30

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Solution

The fourth proportional to 813.90, 1,121.88 and 666.30 is: 918.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.90 : 1,121.88 = 666.30 : x
  2. Step 2: Convert to fraction form
    813.90/1,121.88 = 666.30/x
  3. Step 3: Cross multiply
    813.90x = 1,121.88 × 666.30
  4. Step 4: Simplify right side
    813.90x = 747,508.64
  5. Step 5: Solve for x
    x = 747,508.64/813.90
  6. Step 6: Final answer
    x = 918.43

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.