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Finding the Fourth Proportional to 76.65, 106.40 and 71.79

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Solution

The fourth proportional to 76.65, 106.40 and 71.79 is: 99.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.65 : 106.40 = 71.79 : x
  2. Step 2: Convert to fraction form
    76.65/106.40 = 71.79/x
  3. Step 3: Cross multiply
    76.65x = 106.40 × 71.79
  4. Step 4: Simplify right side
    76.65x = 7,638.64
  5. Step 5: Solve for x
    x = 7,638.64/76.65
  6. Step 6: Final answer
    x = 99.66

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.