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Finding the Fourth Proportional to 103.15, 142.28 and 78.53

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Solution

The fourth proportional to 103.15, 142.28 and 78.53 is: 108.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.15 : 142.28 = 78.53 : x
  2. Step 2: Convert to fraction form
    103.15/142.28 = 78.53/x
  3. Step 3: Cross multiply
    103.15x = 142.28 × 78.53
  4. Step 4: Simplify right side
    103.15x = 11,172.86
  5. Step 5: Solve for x
    x = 11,172.86/103.15
  6. Step 6: Final answer
    x = 108.32

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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.