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Finding the Fourth Proportional to 102.89, 142.18 and 78.28

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Solution

The fourth proportional to 102.89, 142.18 and 78.28 is: 108.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    102.89 : 142.18 = 78.28 : x
  2. Step 2: Convert to fraction form
    102.89/142.18 = 78.28/x
  3. Step 3: Cross multiply
    102.89x = 142.18 × 78.28
  4. Step 4: Simplify right side
    102.89x = 11,129.30
  5. Step 5: Solve for x
    x = 11,129.30/102.89
  6. Step 6: Final answer
    x = 108.17

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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.