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Finding the Fourth Proportional to 685.47, 945.72 and 405.80

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Solution

The fourth proportional to 685.47, 945.72 and 405.80 is: 559.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.47 : 945.72 = 405.80 : x
  2. Step 2: Convert to fraction form
    685.47/945.72 = 405.80/x
  3. Step 3: Cross multiply
    685.47x = 945.72 × 405.80
  4. Step 4: Simplify right side
    685.47x = 383,771.99
  5. Step 5: Solve for x
    x = 383,771.99/685.47
  6. Step 6: Final answer
    x = 559.86

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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.