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Finding the Fourth Proportional to 115.25, 172.29 and 86.35

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Solution

The fourth proportional to 115.25, 172.29 and 86.35 is: 129.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    115.25 : 172.29 = 86.35 : x
  2. Step 2: Convert to fraction form
    115.25/172.29 = 86.35/x
  3. Step 3: Cross multiply
    115.25x = 172.29 × 86.35
  4. Step 4: Simplify right side
    115.25x = 14,876.81
  5. Step 5: Solve for x
    x = 14,876.81/115.25
  6. Step 6: Final answer
    x = 129.08

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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.