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Finding the Fourth Proportional to 77.90, 116.66 and 71.21

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Solution

The fourth proportional to 77.90, 116.66 and 71.21 is: 106.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.90 : 116.66 = 71.21 : x
  2. Step 2: Convert to fraction form
    77.90/116.66 = 71.21/x
  3. Step 3: Cross multiply
    77.90x = 116.66 × 71.21
  4. Step 4: Simplify right side
    77.90x = 8,307.83
  5. Step 5: Solve for x
    x = 8,307.83/77.90
  6. Step 6: Final answer
    x = 106.65

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.