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Finding the Fourth Proportional to 685.34, 945.80 and 390.70

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Solution

The fourth proportional to 685.34, 945.80 and 390.70 is: 539.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.34 : 945.80 = 390.70 : x
  2. Step 2: Convert to fraction form
    685.34/945.80 = 390.70/x
  3. Step 3: Cross multiply
    685.34x = 945.80 × 390.70
  4. Step 4: Simplify right side
    685.34x = 369,523.19
  5. Step 5: Solve for x
    x = 369,523.19/685.34
  6. Step 6: Final answer
    x = 539.19

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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.