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Finding the Fourth Proportional to 390.78, 539.28 and 216.12

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Solution

The fourth proportional to 390.78, 539.28 and 216.12 is: 298.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.78 : 539.28 = 216.12 : x
  2. Step 2: Convert to fraction form
    390.78/539.28 = 216.12/x
  3. Step 3: Cross multiply
    390.78x = 539.28 × 216.12
  4. Step 4: Simplify right side
    390.78x = 116,549.19
  5. Step 5: Solve for x
    x = 116,549.19/390.78
  6. Step 6: Final answer
    x = 298.25

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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.