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Finding the Fourth Proportional to 123.68, 170.57 and 86.78

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Solution

The fourth proportional to 123.68, 170.57 and 86.78 is: 119.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    123.68 : 170.57 = 86.78 : x
  2. Step 2: Convert to fraction form
    123.68/170.57 = 86.78/x
  3. Step 3: Cross multiply
    123.68x = 170.57 × 86.78
  4. Step 4: Simplify right side
    123.68x = 14,801.43
  5. Step 5: Solve for x
    x = 14,801.43/123.68
  6. Step 6: Final answer
    x = 119.67

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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.