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Finding the Fourth Proportional to 128.60, 177.36 and 87.08

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Solution

The fourth proportional to 128.60, 177.36 and 87.08 is: 120.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.60 : 177.36 = 87.08 : x
  2. Step 2: Convert to fraction form
    128.60/177.36 = 87.08/x
  3. Step 3: Cross multiply
    128.60x = 177.36 × 87.08
  4. Step 4: Simplify right side
    128.60x = 15,443.62
  5. Step 5: Solve for x
    x = 15,443.62/128.60
  6. Step 6: Final answer
    x = 120.10

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.