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Finding the Fourth Proportional to 103.68, 142.56 and 78.84

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Solution

The fourth proportional to 103.68, 142.56 and 78.84 is: 108.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.68 : 142.56 = 78.84 : x
  2. Step 2: Convert to fraction form
    103.68/142.56 = 78.84/x
  3. Step 3: Cross multiply
    103.68x = 142.56 × 78.84
  4. Step 4: Simplify right side
    103.68x = 11,239.43
  5. Step 5: Solve for x
    x = 11,239.43/103.68
  6. Step 6: Final answer
    x = 108.41

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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.