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Finding the Fourth Proportional to 91.86, 136.86 and 87.18

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Solution

The fourth proportional to 91.86, 136.86 and 87.18 is: 129.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.86 : 136.86 = 87.18 : x
  2. Step 2: Convert to fraction form
    91.86/136.86 = 87.18/x
  3. Step 3: Cross multiply
    91.86x = 136.86 × 87.18
  4. Step 4: Simplify right side
    91.86x = 11,931.45
  5. Step 5: Solve for x
    x = 11,931.45/91.86
  6. Step 6: Final answer
    x = 129.89

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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.