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Finding the Fourth Proportional to 685.35, 945.84 and 390.63

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Solution

The fourth proportional to 685.35, 945.84 and 390.63 is: 539.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.35 : 945.84 = 390.63 : x
  2. Step 2: Convert to fraction form
    685.35/945.84 = 390.63/x
  3. Step 3: Cross multiply
    685.35x = 945.84 × 390.63
  4. Step 4: Simplify right side
    685.35x = 369,473.48
  5. Step 5: Solve for x
    x = 369,473.48/685.35
  6. Step 6: Final answer
    x = 539.10

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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.