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Finding the Fourth Proportional to 685.12, 945.36 and 390.28

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Solution

The fourth proportional to 685.12, 945.36 and 390.28 is: 538.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.12 : 945.36 = 390.28 : x
  2. Step 2: Convert to fraction form
    685.12/945.36 = 390.28/x
  3. Step 3: Cross multiply
    685.12x = 945.36 × 390.28
  4. Step 4: Simplify right side
    685.12x = 368,955.10
  5. Step 5: Solve for x
    x = 368,955.10/685.12
  6. Step 6: Final answer
    x = 538.53

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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.