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Finding the Fourth Proportional to 815.40, 1,221.66 and 557.64

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Solution

The fourth proportional to 815.40, 1,221.66 and 557.64 is: 835.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.40 : 1,221.66 = 557.64 : x
  2. Step 2: Convert to fraction form
    815.40/1,221.66 = 557.64/x
  3. Step 3: Cross multiply
    815.40x = 1,221.66 × 557.64
  4. Step 4: Simplify right side
    815.40x = 681,246.48
  5. Step 5: Solve for x
    x = 681,246.48/815.40
  6. Step 6: Final answer
    x = 835.48

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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.