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Finding the Fourth Proportional to 128.99, 193.70 and 123.21

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Solution

The fourth proportional to 128.99, 193.70 and 123.21 is: 185.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.99 : 193.70 = 123.21 : x
  2. Step 2: Convert to fraction form
    128.99/193.70 = 123.21/x
  3. Step 3: Cross multiply
    128.99x = 193.70 × 123.21
  4. Step 4: Simplify right side
    128.99x = 23,866.09
  5. Step 5: Solve for x
    x = 23,866.09/128.99
  6. Step 6: Final answer
    x = 185.02

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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.