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Finding the Fourth Proportional to 71.90, 99.15 and 66.50

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Solution

The fourth proportional to 71.90, 99.15 and 66.50 is: 91.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    71.90 : 99.15 = 66.50 : x
  2. Step 2: Convert to fraction form
    71.90/99.15 = 66.50/x
  3. Step 3: Cross multiply
    71.90x = 99.15 × 66.50
  4. Step 4: Simplify right side
    71.90x = 6,593.48
  5. Step 5: Solve for x
    x = 6,593.48/71.90
  6. Step 6: Final answer
    x = 91.70

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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.