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Finding the Fourth Proportional to 521.42, 780.91 and 398.70

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Solution

The fourth proportional to 521.42, 780.91 and 398.70 is: 597.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    521.42 : 780.91 = 398.70 : x
  2. Step 2: Convert to fraction form
    521.42/780.91 = 398.70/x
  3. Step 3: Cross multiply
    521.42x = 780.91 × 398.70
  4. Step 4: Simplify right side
    521.42x = 311,347.82
  5. Step 5: Solve for x
    x = 311,347.82/521.42
  6. Step 6: Final answer
    x = 597.12

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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.