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Finding the Fourth Proportional to 100.36, 138.38 and 87.87

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Solution

The fourth proportional to 100.36, 138.38 and 87.87 is: 121.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.36 : 138.38 = 87.87 : x
  2. Step 2: Convert to fraction form
    100.36/138.38 = 87.87/x
  3. Step 3: Cross multiply
    100.36x = 138.38 × 87.87
  4. Step 4: Simplify right side
    100.36x = 12,159.45
  5. Step 5: Solve for x
    x = 12,159.45/100.36
  6. Step 6: Final answer
    x = 121.16

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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.