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Finding the Fourth Proportional to 685, 945.36 and 390.16

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Solution

The fourth proportional to 685, 945.36 and 390.16 is: 538.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    685 : 945.36 = 390.16 : x
  2. Step 2: Convert to fraction form
    685/945.36 = 390.16/x
  3. Step 3: Cross multiply
    685x = 945.36 × 390.16
  4. Step 4: Simplify right side
    685x = 368,841.66
  5. Step 5: Solve for x
    x = 368,841.66/685
  6. Step 6: Final answer
    x = 538.45

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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.