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Finding the Fourth Proportional to 390.88, 539.40 and 216.20

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Solution

The fourth proportional to 390.88, 539.40 and 216.20 is: 298.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.88 : 539.40 = 216.20 : x
  2. Step 2: Convert to fraction form
    390.88/539.40 = 216.20/x
  3. Step 3: Cross multiply
    390.88x = 539.40 × 216.20
  4. Step 4: Simplify right side
    390.88x = 116,618.28
  5. Step 5: Solve for x
    x = 116,618.28/390.88
  6. Step 6: Final answer
    x = 298.35

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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.