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Finding the Fourth Proportional to 128.65, 177.36 and 99.19

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Solution

The fourth proportional to 128.65, 177.36 and 99.19 is: 136.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.65 : 177.36 = 99.19 : x
  2. Step 2: Convert to fraction form
    128.65/177.36 = 99.19/x
  3. Step 3: Cross multiply
    128.65x = 177.36 × 99.19
  4. Step 4: Simplify right side
    128.65x = 17,592.34
  5. Step 5: Solve for x
    x = 17,592.34/128.65
  6. Step 6: Final answer
    x = 136.75

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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.