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Finding the Fourth Proportional to 815.95, 1,221.58 and 621.70

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Solution

The fourth proportional to 815.95, 1,221.58 and 621.70 is: 930.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.95 : 1,221.58 = 621.70 : x
  2. Step 2: Convert to fraction form
    815.95/1,221.58 = 621.70/x
  3. Step 3: Cross multiply
    815.95x = 1,221.58 × 621.70
  4. Step 4: Simplify right side
    815.95x = 759,456.29
  5. Step 5: Solve for x
    x = 759,456.29/815.95
  6. Step 6: Final answer
    x = 930.76

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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.