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Finding the Fourth Proportional to 643.76, 888.64 and 395.28

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Solution

The fourth proportional to 643.76, 888.64 and 395.28 is: 545.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.76 : 888.64 = 395.28 : x
  2. Step 2: Convert to fraction form
    643.76/888.64 = 395.28/x
  3. Step 3: Cross multiply
    643.76x = 888.64 × 395.28
  4. Step 4: Simplify right side
    643.76x = 351,261.62
  5. Step 5: Solve for x
    x = 351,261.62/643.76
  6. Step 6: Final answer
    x = 545.64

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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.