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Finding the Fourth Proportional to 261.72, 392.70 and 138.30

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Solution

The fourth proportional to 261.72, 392.70 and 138.30 is: 207.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.72 : 392.70 = 138.30 : x
  2. Step 2: Convert to fraction form
    261.72/392.70 = 138.30/x
  3. Step 3: Cross multiply
    261.72x = 392.70 × 138.30
  4. Step 4: Simplify right side
    261.72x = 54,309.46
  5. Step 5: Solve for x
    x = 54,309.46/261.72
  6. Step 6: Final answer
    x = 207.51

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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.