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Finding the Fourth Proportional to 643.12, 887.08 and 621.72

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Solution

The fourth proportional to 643.12, 887.08 and 621.72 is: 857.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.12 : 887.08 = 621.72 : x
  2. Step 2: Convert to fraction form
    643.12/887.08 = 621.72/x
  3. Step 3: Cross multiply
    643.12x = 887.08 × 621.72
  4. Step 4: Simplify right side
    643.12x = 551,515.38
  5. Step 5: Solve for x
    x = 551,515.38/643.12
  6. Step 6: Final answer
    x = 857.56

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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.