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Finding the Fourth Proportional to 128.86, 177.75 and 84.60

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Solution

The fourth proportional to 128.86, 177.75 and 84.60 is: 116.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.86 : 177.75 = 84.60 : x
  2. Step 2: Convert to fraction form
    128.86/177.75 = 84.60/x
  3. Step 3: Cross multiply
    128.86x = 177.75 × 84.60
  4. Step 4: Simplify right side
    128.86x = 15,038.00
  5. Step 5: Solve for x
    x = 15,038.00/128.86
  6. Step 6: Final answer
    x = 116.70

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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.