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Finding the Fourth Proportional to 128.40, 177.08 and 108.74

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Solution

The fourth proportional to 128.40, 177.08 and 108.74 is: 149.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.40 : 177.08 = 108.74 : x
  2. Step 2: Convert to fraction form
    128.40/177.08 = 108.74/x
  3. Step 3: Cross multiply
    128.40x = 177.08 × 108.74
  4. Step 4: Simplify right side
    128.40x = 19,254.25
  5. Step 5: Solve for x
    x = 19,254.25/128.40
  6. Step 6: Final answer
    x = 149.96

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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.