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Finding the Fourth Proportional to 390.65, 539.09 and 215.99

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Solution

The fourth proportional to 390.65, 539.09 and 215.99 is: 298.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.65 : 539.09 = 215.99 : x
  2. Step 2: Convert to fraction form
    390.65/539.09 = 215.99/x
  3. Step 3: Cross multiply
    390.65x = 539.09 × 215.99
  4. Step 4: Simplify right side
    390.65x = 116,439.13
  5. Step 5: Solve for x
    x = 116,439.13/390.65
  6. Step 6: Final answer
    x = 298.07

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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.