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Finding the Fourth Proportional to 100.38, 138.60 and 79.76

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Solution

The fourth proportional to 100.38, 138.60 and 79.76 is: 110.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.38 : 138.60 = 79.76 : x
  2. Step 2: Convert to fraction form
    100.38/138.60 = 79.76/x
  3. Step 3: Cross multiply
    100.38x = 138.60 × 79.76
  4. Step 4: Simplify right side
    100.38x = 11,054.74
  5. Step 5: Solve for x
    x = 11,054.74/100.38
  6. Step 6: Final answer
    x = 110.13

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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.