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Finding the Fourth Proportional to 685.34, 945.79 and 390.65

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Solution

The fourth proportional to 685.34, 945.79 and 390.65 is: 539.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.34 : 945.79 = 390.65 : x
  2. Step 2: Convert to fraction form
    685.34/945.79 = 390.65/x
  3. Step 3: Cross multiply
    685.34x = 945.79 × 390.65
  4. Step 4: Simplify right side
    685.34x = 369,472.86
  5. Step 5: Solve for x
    x = 369,472.86/685.34
  6. Step 6: Final answer
    x = 539.11

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Double scale
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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.