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Finding the Fourth Proportional to 515.70, 712.80 and 491.40

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Solution

The fourth proportional to 515.70, 712.80 and 491.40 is: 679.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    515.70 : 712.80 = 491.40 : x
  2. Step 2: Convert to fraction form
    515.70/712.80 = 491.40/x
  3. Step 3: Cross multiply
    515.70x = 712.80 × 491.40
  4. Step 4: Simplify right side
    515.70x = 350,269.92
  5. Step 5: Solve for x
    x = 350,269.92/515.70
  6. Step 6: Final answer
    x = 679.21

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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.