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Finding the Fourth Proportional to 115.05, 172.71 and 78.87

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Solution

The fourth proportional to 115.05, 172.71 and 78.87 is: 118.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    115.05 : 172.71 = 78.87 : x
  2. Step 2: Convert to fraction form
    115.05/172.71 = 78.87/x
  3. Step 3: Cross multiply
    115.05x = 172.71 × 78.87
  4. Step 4: Simplify right side
    115.05x = 13,621.64
  5. Step 5: Solve for x
    x = 13,621.64/115.05
  6. Step 6: Final answer
    x = 118.40

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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.