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Finding the Fourth Proportional to 261.72, 390.24 and 261.36

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Solution

The fourth proportional to 261.72, 390.24 and 261.36 is: 389.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.72 : 390.24 = 261.36 : x
  2. Step 2: Convert to fraction form
    261.72/390.24 = 261.36/x
  3. Step 3: Cross multiply
    261.72x = 390.24 × 261.36
  4. Step 4: Simplify right side
    261.72x = 101,993.13
  5. Step 5: Solve for x
    x = 101,993.13/261.72
  6. Step 6: Final answer
    x = 389.70

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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.