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Finding the Fourth Proportional to 100.51, 138.60 and 72.86

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Solution

The fourth proportional to 100.51, 138.60 and 72.86 is: 100.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.51 : 138.60 = 72.86 : x
  2. Step 2: Convert to fraction form
    100.51/138.60 = 72.86/x
  3. Step 3: Cross multiply
    100.51x = 138.60 × 72.86
  4. Step 4: Simplify right side
    100.51x = 10,097.70
  5. Step 5: Solve for x
    x = 10,097.70/100.51
  6. Step 6: Final answer
    x = 100.47

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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.