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Finding the Fourth Proportional to 123.96, 170.88 and 91.20

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Solution

The fourth proportional to 123.96, 170.88 and 91.20 is: 125.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    123.96 : 170.88 = 91.20 : x
  2. Step 2: Convert to fraction form
    123.96/170.88 = 91.20/x
  3. Step 3: Cross multiply
    123.96x = 170.88 × 91.20
  4. Step 4: Simplify right side
    123.96x = 15,584.26
  5. Step 5: Solve for x
    x = 15,584.26/123.96
  6. Step 6: Final answer
    x = 125.72

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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.