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Finding the Fourth Proportional to 391.58, 540.69 and 317.78

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Solution

The fourth proportional to 391.58, 540.69 and 317.78 is: 438.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.58 : 540.69 = 317.78 : x
  2. Step 2: Convert to fraction form
    391.58/540.69 = 317.78/x
  3. Step 3: Cross multiply
    391.58x = 540.69 × 317.78
  4. Step 4: Simplify right side
    391.58x = 171,820.47
  5. Step 5: Solve for x
    x = 171,820.47/391.58
  6. Step 6: Final answer
    x = 438.79

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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.