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Finding the Fourth Proportional to 123.78, 170.76 and 72

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Solution

The fourth proportional to 123.78, 170.76 and 72 is: 99.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    123.78 : 170.76 = 72 : x
  2. Step 2: Convert to fraction form
    123.78/170.76 = 72/x
  3. Step 3: Cross multiply
    123.78x = 170.76 × 72
  4. Step 4: Simplify right side
    123.78x = 12,294.72
  5. Step 5: Solve for x
    x = 12,294.72/123.78
  6. Step 6: Final answer
    x = 99.33

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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.