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Finding the Fourth Proportional to 128.36, 177.28 and 99.60

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Solution

The fourth proportional to 128.36, 177.28 and 99.60 is: 137.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.36 : 177.28 = 99.60 : x
  2. Step 2: Convert to fraction form
    128.36/177.28 = 99.60/x
  3. Step 3: Cross multiply
    128.36x = 177.28 × 99.60
  4. Step 4: Simplify right side
    128.36x = 17,657.09
  5. Step 5: Solve for x
    x = 17,657.09/128.36
  6. Step 6: Final answer
    x = 137.56

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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.