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Finding the Fourth Proportional to 643.80, 892.18 and 631.50

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Solution

The fourth proportional to 643.80, 892.18 and 631.50 is: 875.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.80 : 892.18 = 631.50 : x
  2. Step 2: Convert to fraction form
    643.80/892.18 = 631.50/x
  3. Step 3: Cross multiply
    643.80x = 892.18 × 631.50
  4. Step 4: Simplify right side
    643.80x = 563,411.67
  5. Step 5: Solve for x
    x = 563,411.67/643.80
  6. Step 6: Final answer
    x = 875.13

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.