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Finding the Fourth Proportional to 100.13, 138.13 and 65.15

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Solution

The fourth proportional to 100.13, 138.13 and 65.15 is: 89.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.13 : 138.13 = 65.15 : x
  2. Step 2: Convert to fraction form
    100.13/138.13 = 65.15/x
  3. Step 3: Cross multiply
    100.13x = 138.13 × 65.15
  4. Step 4: Simplify right side
    100.13x = 8,999.35
  5. Step 5: Solve for x
    x = 8,999.35/100.13
  6. Step 6: Final answer
    x = 89.88

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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.