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Finding the Fourth Proportional to 115.10, 172.29 and 86.05

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Solution

The fourth proportional to 115.10, 172.29 and 86.05 is: 128.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    115.10 : 172.29 = 86.05 : x
  2. Step 2: Convert to fraction form
    115.10/172.29 = 86.05/x
  3. Step 3: Cross multiply
    115.10x = 172.29 × 86.05
  4. Step 4: Simplify right side
    115.10x = 14,824.69
  5. Step 5: Solve for x
    x = 14,824.69/115.10
  6. Step 6: Final answer
    x = 128.80

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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.