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Finding the Fourth Proportional to 128.50, 177.42 and 89.74

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Solution

The fourth proportional to 128.50, 177.42 and 89.74 is: 123.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.50 : 177.42 = 89.74 : x
  2. Step 2: Convert to fraction form
    128.50/177.42 = 89.74/x
  3. Step 3: Cross multiply
    128.50x = 177.42 × 89.74
  4. Step 4: Simplify right side
    128.50x = 15,921.67
  5. Step 5: Solve for x
    x = 15,921.67/128.50
  6. Step 6: Final answer
    x = 123.90

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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.