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Finding the Fourth Proportional to 123.78, 170.68 and 86.47

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Solution

The fourth proportional to 123.78, 170.68 and 86.47 is: 119.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    123.78 : 170.68 = 86.47 : x
  2. Step 2: Convert to fraction form
    123.78/170.68 = 86.47/x
  3. Step 3: Cross multiply
    123.78x = 170.68 × 86.47
  4. Step 4: Simplify right side
    123.78x = 14,758.70
  5. Step 5: Solve for x
    x = 14,758.70/123.78
  6. Step 6: Final answer
    x = 119.23

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These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.