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Finding the Fourth Proportional to 685.64, 946.08 and 390.84

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Solution

The fourth proportional to 685.64, 946.08 and 390.84 is: 539.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.64 : 946.08 = 390.84 : x
  2. Step 2: Convert to fraction form
    685.64/946.08 = 390.84/x
  3. Step 3: Cross multiply
    685.64x = 946.08 × 390.84
  4. Step 4: Simplify right side
    685.64x = 369,765.91
  5. Step 5: Solve for x
    x = 369,765.91/685.64
  6. Step 6: Final answer
    x = 539.30

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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.