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Finding the Fourth Proportional to 128.59, 177.42 and 87.07

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Solution

The fourth proportional to 128.59, 177.42 and 87.07 is: 120.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.59 : 177.42 = 87.07 : x
  2. Step 2: Convert to fraction form
    128.59/177.42 = 87.07/x
  3. Step 3: Cross multiply
    128.59x = 177.42 × 87.07
  4. Step 4: Simplify right side
    128.59x = 15,448.37
  5. Step 5: Solve for x
    x = 15,448.37/128.59
  6. Step 6: Final answer
    x = 120.13

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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.