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Finding the Fourth Proportional to 231.90, 319.98 and 128.40

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Solution

The fourth proportional to 231.90, 319.98 and 128.40 is: 177.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    231.90 : 319.98 = 128.40 : x
  2. Step 2: Convert to fraction form
    231.90/319.98 = 128.40/x
  3. Step 3: Cross multiply
    231.90x = 319.98 × 128.40
  4. Step 4: Simplify right side
    231.90x = 41,085.43
  5. Step 5: Solve for x
    x = 41,085.43/231.90
  6. Step 6: Final answer
    x = 177.17

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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.