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Finding the Fourth Proportional to 685.14, 945.39 and 390.34

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Solution

The fourth proportional to 685.14, 945.39 and 390.34 is: 538.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.14 : 945.39 = 390.34 : x
  2. Step 2: Convert to fraction form
    685.14/945.39 = 390.34/x
  3. Step 3: Cross multiply
    685.14x = 945.39 × 390.34
  4. Step 4: Simplify right side
    685.14x = 369,023.53
  5. Step 5: Solve for x
    x = 369,023.53/685.14
  6. Step 6: Final answer
    x = 538.61

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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.