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Finding the Fourth Proportional to 128.59, 177.54 and 87.18

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Solution

The fourth proportional to 128.59, 177.54 and 87.18 is: 120.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.59 : 177.54 = 87.18 : x
  2. Step 2: Convert to fraction form
    128.59/177.54 = 87.18/x
  3. Step 3: Cross multiply
    128.59x = 177.54 × 87.18
  4. Step 4: Simplify right side
    128.59x = 15,477.27
  5. Step 5: Solve for x
    x = 15,477.27/128.59
  6. Step 6: Final answer
    x = 120.36

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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.