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Finding the Fourth Proportional to 115.19, 172.61 and 86.16

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Solution

The fourth proportional to 115.19, 172.61 and 86.16 is: 129.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    115.19 : 172.61 = 86.16 : x
  2. Step 2: Convert to fraction form
    115.19/172.61 = 86.16/x
  3. Step 3: Cross multiply
    115.19x = 172.61 × 86.16
  4. Step 4: Simplify right side
    115.19x = 14,871.65
  5. Step 5: Solve for x
    x = 14,871.65/115.19
  6. Step 6: Final answer
    x = 129.11

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.