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Finding the Fourth Proportional to 115.20, 172.08 and 91.08

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Solution

The fourth proportional to 115.20, 172.08 and 91.08 is: 136.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    115.20 : 172.08 = 91.08 : x
  2. Step 2: Convert to fraction form
    115.20/172.08 = 91.08/x
  3. Step 3: Cross multiply
    115.20x = 172.08 × 91.08
  4. Step 4: Simplify right side
    115.20x = 15,673.05
  5. Step 5: Solve for x
    x = 15,673.05/115.20
  6. Step 6: Final answer
    x = 136.05

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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.