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Finding the Fourth Proportional to 128.70, 193.14 and 90.23

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Solution

The fourth proportional to 128.70, 193.14 and 90.23 is: 135.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.70 : 193.14 = 90.23 : x
  2. Step 2: Convert to fraction form
    128.70/193.14 = 90.23/x
  3. Step 3: Cross multiply
    128.70x = 193.14 × 90.23
  4. Step 4: Simplify right side
    128.70x = 17,426.06
  5. Step 5: Solve for x
    x = 17,426.06/128.70
  6. Step 6: Final answer
    x = 135.40

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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.