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Finding the Fourth Proportional to 391.91, 540.63 and 251.78

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Solution

The fourth proportional to 391.91, 540.63 and 251.78 is: 347.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.91 : 540.63 = 251.78 : x
  2. Step 2: Convert to fraction form
    391.91/540.63 = 251.78/x
  3. Step 3: Cross multiply
    391.91x = 540.63 × 251.78
  4. Step 4: Simplify right side
    391.91x = 136,117.12
  5. Step 5: Solve for x
    x = 136,117.12/391.91
  6. Step 6: Final answer
    x = 347.32

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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.