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Finding the Fourth Proportional to 685.11, 945.40 and 390.37

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Solution

The fourth proportional to 685.11, 945.40 and 390.37 is: 538.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.11 : 945.40 = 390.37 : x
  2. Step 2: Convert to fraction form
    685.11/945.40 = 390.37/x
  3. Step 3: Cross multiply
    685.11x = 945.40 × 390.37
  4. Step 4: Simplify right side
    685.11x = 369,055.80
  5. Step 5: Solve for x
    x = 369,055.80/685.11
  6. Step 6: Final answer
    x = 538.68

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Half scale
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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.