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Finding the Fourth Proportional to 103.86, 143.28 and 72.78

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Solution

The fourth proportional to 103.86, 143.28 and 72.78 is: 100.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.86 : 143.28 = 72.78 : x
  2. Step 2: Convert to fraction form
    103.86/143.28 = 72.78/x
  3. Step 3: Cross multiply
    103.86x = 143.28 × 72.78
  4. Step 4: Simplify right side
    103.86x = 10,427.92
  5. Step 5: Solve for x
    x = 10,427.92/103.86
  6. Step 6: Final answer
    x = 100.40

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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.