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Finding the Fourth Proportional to 521.80, 780.78 and 399.88

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Solution

The fourth proportional to 521.80, 780.78 and 399.88 is: 598.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    521.80 : 780.78 = 399.88 : x
  2. Step 2: Convert to fraction form
    521.80/780.78 = 399.88/x
  3. Step 3: Cross multiply
    521.80x = 780.78 × 399.88
  4. Step 4: Simplify right side
    521.80x = 312,218.31
  5. Step 5: Solve for x
    x = 312,218.31/521.80
  6. Step 6: Final answer
    x = 598.35

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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.