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Finding the Fourth Proportional to 128.80, 192.99 and 90.34

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Solution

The fourth proportional to 128.80, 192.99 and 90.34 is: 135.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.80 : 192.99 = 90.34 : x
  2. Step 2: Convert to fraction form
    128.80/192.99 = 90.34/x
  3. Step 3: Cross multiply
    128.80x = 192.99 × 90.34
  4. Step 4: Simplify right side
    128.80x = 17,434.72
  5. Step 5: Solve for x
    x = 17,434.72/128.80
  6. Step 6: Final answer
    x = 135.36

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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.