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Finding the Fourth Proportional to 685.94, 946.40 and 391.23

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Solution

The fourth proportional to 685.94, 946.40 and 391.23 is: 539.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.94 : 946.40 = 391.23 : x
  2. Step 2: Convert to fraction form
    685.94/946.40 = 391.23/x
  3. Step 3: Cross multiply
    685.94x = 946.40 × 391.23
  4. Step 4: Simplify right side
    685.94x = 370,258.12
  5. Step 5: Solve for x
    x = 370,258.12/685.94
  6. Step 6: Final answer
    x = 539.79

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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.