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Finding the Fourth Proportional to 86.80, 129.62 and 76

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Solution

The fourth proportional to 86.80, 129.62 and 76 is: 113.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.80 : 129.62 = 76 : x
  2. Step 2: Convert to fraction form
    86.80/129.62 = 76/x
  3. Step 3: Cross multiply
    86.80x = 129.62 × 76
  4. Step 4: Simplify right side
    86.80x = 9,851.12
  5. Step 5: Solve for x
    x = 9,851.12/86.80
  6. Step 6: Final answer
    x = 113.49

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.