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Finding the Fourth Proportional to 91.88, 136.72 and 86.16

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Solution

The fourth proportional to 91.88, 136.72 and 86.16 is: 128.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.88 : 136.72 = 86.16 : x
  2. Step 2: Convert to fraction form
    91.88/136.72 = 86.16/x
  3. Step 3: Cross multiply
    91.88x = 136.72 × 86.16
  4. Step 4: Simplify right side
    91.88x = 11,779.80
  5. Step 5: Solve for x
    x = 11,779.80/91.88
  6. Step 6: Final answer
    x = 128.21

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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.