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Finding the Fourth Proportional to 813.56, 1,121.70 and 665.86

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Solution

The fourth proportional to 813.56, 1,121.70 and 665.86 is: 918.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.56 : 1,121.70 = 665.86 : x
  2. Step 2: Convert to fraction form
    813.56/1,121.70 = 665.86/x
  3. Step 3: Cross multiply
    813.56x = 1,121.70 × 665.86
  4. Step 4: Simplify right side
    813.56x = 746,895.16
  5. Step 5: Solve for x
    x = 746,895.16/813.56
  6. Step 6: Final answer
    x = 918.06

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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.