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Finding the Fourth Proportional to 123.90, 170.85 and 91.23

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Solution

The fourth proportional to 123.90, 170.85 and 91.23 is: 125.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    123.90 : 170.85 = 91.23 : x
  2. Step 2: Convert to fraction form
    123.90/170.85 = 91.23/x
  3. Step 3: Cross multiply
    123.90x = 170.85 × 91.23
  4. Step 4: Simplify right side
    123.90x = 15,586.65
  5. Step 5: Solve for x
    x = 15,586.65/123.90
  6. Step 6: Final answer
    x = 125.80

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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.