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Finding the Fourth Proportional to 72.18, 99.45 and 61.11

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Solution

The fourth proportional to 72.18, 99.45 and 61.11 is: 84.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.18 : 99.45 = 61.11 : x
  2. Step 2: Convert to fraction form
    72.18/99.45 = 61.11/x
  3. Step 3: Cross multiply
    72.18x = 99.45 × 61.11
  4. Step 4: Simplify right side
    72.18x = 6,077.39
  5. Step 5: Solve for x
    x = 6,077.39/72.18
  6. Step 6: Final answer
    x = 84.20

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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.