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Finding the Fourth Proportional to 517.75, 780.19 and 428.45

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Solution

The fourth proportional to 517.75, 780.19 and 428.45 is: 645.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    517.75 : 780.19 = 428.45 : x
  2. Step 2: Convert to fraction form
    517.75/780.19 = 428.45/x
  3. Step 3: Cross multiply
    517.75x = 780.19 × 428.45
  4. Step 4: Simplify right side
    517.75x = 334,270.26
  5. Step 5: Solve for x
    x = 334,270.26/517.75
  6. Step 6: Final answer
    x = 645.63

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.