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Finding the Fourth Proportional to 171.78, 257.76 and 99.78

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Solution

The fourth proportional to 171.78, 257.76 and 99.78 is: 149.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    171.78 : 257.76 = 99.78 : x
  2. Step 2: Convert to fraction form
    171.78/257.76 = 99.78/x
  3. Step 3: Cross multiply
    171.78x = 257.76 × 99.78
  4. Step 4: Simplify right side
    171.78x = 25,719.29
  5. Step 5: Solve for x
    x = 25,719.29/171.78
  6. Step 6: Final answer
    x = 149.72

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.