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Finding the Fourth Proportional to 123.78, 170.76 and 76.50

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Solution

The fourth proportional to 123.78, 170.76 and 76.50 is: 105.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    123.78 : 170.76 = 76.50 : x
  2. Step 2: Convert to fraction form
    123.78/170.76 = 76.50/x
  3. Step 3: Cross multiply
    123.78x = 170.76 × 76.50
  4. Step 4: Simplify right side
    123.78x = 13,063.14
  5. Step 5: Solve for x
    x = 13,063.14/123.78
  6. Step 6: Final answer
    x = 105.54

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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.