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Finding the Fourth Proportional to 261.87, 390.94 and 220.86

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Solution

The fourth proportional to 261.87, 390.94 and 220.86 is: 329.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.87 : 390.94 = 220.86 : x
  2. Step 2: Convert to fraction form
    261.87/390.94 = 220.86/x
  3. Step 3: Cross multiply
    261.87x = 390.94 × 220.86
  4. Step 4: Simplify right side
    261.87x = 86,343.01
  5. Step 5: Solve for x
    x = 86,343.01/261.87
  6. Step 6: Final answer
    x = 329.72

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.