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Finding the Fourth Proportional to 71.90, 99.15 and 61.57

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Solution

The fourth proportional to 71.90, 99.15 and 61.57 is: 84.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    71.90 : 99.15 = 61.57 : x
  2. Step 2: Convert to fraction form
    71.90/99.15 = 61.57/x
  3. Step 3: Cross multiply
    71.90x = 99.15 × 61.57
  4. Step 4: Simplify right side
    71.90x = 6,104.76
  5. Step 5: Solve for x
    x = 6,104.76/71.90
  6. Step 6: Final answer
    x = 84.91

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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.