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Finding the Fourth Proportional to 521.78, 719.08 and 390.56

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Solution

The fourth proportional to 521.78, 719.08 and 390.56 is: 538.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    521.78 : 719.08 = 390.56 : x
  2. Step 2: Convert to fraction form
    521.78/719.08 = 390.56/x
  3. Step 3: Cross multiply
    521.78x = 719.08 × 390.56
  4. Step 4: Simplify right side
    521.78x = 280,839.31
  5. Step 5: Solve for x
    x = 280,839.31/521.78
  6. Step 6: Final answer
    x = 538.24

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Double scale
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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.