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Finding the Fourth Proportional to 685.79, 946.40 and 391.11

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Solution

The fourth proportional to 685.79, 946.40 and 391.11 is: 539.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.79 : 946.40 = 391.11 : x
  2. Step 2: Convert to fraction form
    685.79/946.40 = 391.11/x
  3. Step 3: Cross multiply
    685.79x = 946.40 × 391.11
  4. Step 4: Simplify right side
    685.79x = 370,144.55
  5. Step 5: Solve for x
    x = 370,144.55/685.79
  6. Step 6: Final answer
    x = 539.74

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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.