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Finding the Fourth Proportional to 521.18, 780.40 and 505.78

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Solution

The fourth proportional to 521.18, 780.40 and 505.78 is: 757.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    521.18 : 780.40 = 505.78 : x
  2. Step 2: Convert to fraction form
    521.18/780.40 = 505.78/x
  3. Step 3: Cross multiply
    521.18x = 780.40 × 505.78
  4. Step 4: Simplify right side
    521.18x = 394,710.71
  5. Step 5: Solve for x
    x = 394,710.71/521.18
  6. Step 6: Final answer
    x = 757.34

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.