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Finding the Fourth Proportional to 390.96, 587.48 and 217.80

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Solution

The fourth proportional to 390.96, 587.48 and 217.80 is: 327.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.96 : 587.48 = 217.80 : x
  2. Step 2: Convert to fraction form
    390.96/587.48 = 217.80/x
  3. Step 3: Cross multiply
    390.96x = 587.48 × 217.80
  4. Step 4: Simplify right side
    390.96x = 127,953.14
  5. Step 5: Solve for x
    x = 127,953.14/390.96
  6. Step 6: Final answer
    x = 327.28

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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.