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Finding the Fourth Proportional to 431.36, 647.05 and 142.80

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Solution

The fourth proportional to 431.36, 647.05 and 142.80 is: 214.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.36 : 647.05 = 142.80 : x
  2. Step 2: Convert to fraction form
    431.36/647.05 = 142.80/x
  3. Step 3: Cross multiply
    431.36x = 647.05 × 142.80
  4. Step 4: Simplify right side
    431.36x = 92,398.03
  5. Step 5: Solve for x
    x = 92,398.03/431.36
  6. Step 6: Final answer
    x = 214.20

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.