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Finding the Fourth Proportional to 780.90, 1,078.56 and 624.08

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Solution

The fourth proportional to 780.90, 1,078.56 and 624.08 is: 861.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.90 : 1,078.56 = 624.08 : x
  2. Step 2: Convert to fraction form
    780.90/1,078.56 = 624.08/x
  3. Step 3: Cross multiply
    780.90x = 1,078.56 × 624.08
  4. Step 4: Simplify right side
    780.90x = 673,102.33
  5. Step 5: Solve for x
    x = 673,102.33/780.90
  6. Step 6: Final answer
    x = 861.96

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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.