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Finding the Fourth Proportional to 100, 138.06 and 65.56

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Solution

The fourth proportional to 100, 138.06 and 65.56 is: 90.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    100 : 138.06 = 65.56 : x
  2. Step 2: Convert to fraction form
    100/138.06 = 65.56/x
  3. Step 3: Cross multiply
    100x = 138.06 × 65.56
  4. Step 4: Simplify right side
    100x = 9,051.21
  5. Step 5: Solve for x
    x = 9,051.21/100
  6. Step 6: Final answer
    x = 90.51

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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.