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Finding the Fourth Proportional to 685.90, 946.55 and 391.18

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Solution

The fourth proportional to 685.90, 946.55 and 391.18 is: 539.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.90 : 946.55 = 391.18 : x
  2. Step 2: Convert to fraction form
    685.90/946.55 = 391.18/x
  3. Step 3: Cross multiply
    685.90x = 946.55 × 391.18
  4. Step 4: Simplify right side
    685.90x = 370,271.43
  5. Step 5: Solve for x
    x = 370,271.43/685.90
  6. Step 6: Final answer
    x = 539.83

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1.5x scale

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.