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Finding the Fourth Proportional to 187.40, 258.74 and 128.49

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Solution

The fourth proportional to 187.40, 258.74 and 128.49 is: 177.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    187.40 : 258.74 = 128.49 : x
  2. Step 2: Convert to fraction form
    187.40/258.74 = 128.49/x
  3. Step 3: Cross multiply
    187.40x = 258.74 × 128.49
  4. Step 4: Simplify right side
    187.40x = 33,245.10
  5. Step 5: Solve for x
    x = 33,245.10/187.40
  6. Step 6: Final answer
    x = 177.40

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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.