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Finding the Fourth Proportional to 642.88, 881.40 and 631.20

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Solution

The fourth proportional to 642.88, 881.40 and 631.20 is: 865.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.88 : 881.40 = 631.20 : x
  2. Step 2: Convert to fraction form
    642.88/881.40 = 631.20/x
  3. Step 3: Cross multiply
    642.88x = 881.40 × 631.20
  4. Step 4: Simplify right side
    642.88x = 556,339.68
  5. Step 5: Solve for x
    x = 556,339.68/642.88
  6. Step 6: Final answer
    x = 865.39

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.