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Finding the Fourth Proportional to 717.90, 991.12 and 551.78

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Solution

The fourth proportional to 717.90, 991.12 and 551.78 is: 761.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    717.90 : 991.12 = 551.78 : x
  2. Step 2: Convert to fraction form
    717.90/991.12 = 551.78/x
  3. Step 3: Cross multiply
    717.90x = 991.12 × 551.78
  4. Step 4: Simplify right side
    717.90x = 546,880.19
  5. Step 5: Solve for x
    x = 546,880.19/717.90
  6. Step 6: Final answer
    x = 761.78

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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.