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Finding the Fourth Proportional to 685.16, 945.28 and 390.35

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Solution

The fourth proportional to 685.16, 945.28 and 390.35 is: 538.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.16 : 945.28 = 390.35 : x
  2. Step 2: Convert to fraction form
    685.16/945.28 = 390.35/x
  3. Step 3: Cross multiply
    685.16x = 945.28 × 390.35
  4. Step 4: Simplify right side
    685.16x = 368,990.05
  5. Step 5: Solve for x
    x = 368,990.05/685.16
  6. Step 6: Final answer
    x = 538.55

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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.