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Finding the Fourth Proportional to 128.91, 177.74 and 90.03

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Solution

The fourth proportional to 128.91, 177.74 and 90.03 is: 124.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.91 : 177.74 = 90.03 : x
  2. Step 2: Convert to fraction form
    128.91/177.74 = 90.03/x
  3. Step 3: Cross multiply
    128.91x = 177.74 × 90.03
  4. Step 4: Simplify right side
    128.91x = 16,001.48
  5. Step 5: Solve for x
    x = 16,001.48/128.91
  6. Step 6: Final answer
    x = 124.13

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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.