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Finding the Fourth Proportional to 813.92, 1,121.97 and 638.96

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Solution

The fourth proportional to 813.92, 1,121.97 and 638.96 is: 880.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.92 : 1,121.97 = 638.96 : x
  2. Step 2: Convert to fraction form
    813.92/1,121.97 = 638.96/x
  3. Step 3: Cross multiply
    813.92x = 1,121.97 × 638.96
  4. Step 4: Simplify right side
    813.92x = 716,893.95
  5. Step 5: Solve for x
    x = 716,893.95/813.92
  6. Step 6: Final answer
    x = 880.79

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1.5x scale

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.