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Finding the Fourth Proportional to 100.72, 138.84 and 71.56

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Solution

The fourth proportional to 100.72, 138.84 and 71.56 is: 98.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.72 : 138.84 = 71.56 : x
  2. Step 2: Convert to fraction form
    100.72/138.84 = 71.56/x
  3. Step 3: Cross multiply
    100.72x = 138.84 × 71.56
  4. Step 4: Simplify right side
    100.72x = 9,935.39
  5. Step 5: Solve for x
    x = 9,935.39/100.72
  6. Step 6: Final answer
    x = 98.64

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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.