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Finding the Fourth Proportional to 520.45, 780.65 and 212.21

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Solution

The fourth proportional to 520.45, 780.65 and 212.21 is: 318.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    520.45 : 780.65 = 212.21 : x
  2. Step 2: Convert to fraction form
    520.45/780.65 = 212.21/x
  3. Step 3: Cross multiply
    520.45x = 780.65 × 212.21
  4. Step 4: Simplify right side
    520.45x = 165,661.74
  5. Step 5: Solve for x
    x = 165,661.74/520.45
  6. Step 6: Final answer
    x = 318.30

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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.