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Finding the Fourth Proportional to 515.20, 714.40 and 489.60

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Solution

The fourth proportional to 515.20, 714.40 and 489.60 is: 678.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    515.20 : 714.40 = 489.60 : x
  2. Step 2: Convert to fraction form
    515.20/714.40 = 489.60/x
  3. Step 3: Cross multiply
    515.20x = 714.40 × 489.60
  4. Step 4: Simplify right side
    515.20x = 349,770.24
  5. Step 5: Solve for x
    x = 349,770.24/515.20
  6. Step 6: Final answer
    x = 678.90

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.