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Finding the Fourth Proportional to 91.71, 136.70 and 87.69

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Solution

The fourth proportional to 91.71, 136.70 and 87.69 is: 130.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.71 : 136.70 = 87.69 : x
  2. Step 2: Convert to fraction form
    91.71/136.70 = 87.69/x
  3. Step 3: Cross multiply
    91.71x = 136.70 × 87.69
  4. Step 4: Simplify right side
    91.71x = 11,987.22
  5. Step 5: Solve for x
    x = 11,987.22/91.71
  6. Step 6: Final answer
    x = 130.71

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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.