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Finding the Fourth Proportional to 123.76, 170.78 and 71.31

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Solution

The fourth proportional to 123.76, 170.78 and 71.31 is: 98.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    123.76 : 170.78 = 71.31 : x
  2. Step 2: Convert to fraction form
    123.76/170.78 = 71.31/x
  3. Step 3: Cross multiply
    123.76x = 170.78 × 71.31
  4. Step 4: Simplify right side
    123.76x = 12,178.32
  5. Step 5: Solve for x
    x = 12,178.32/123.76
  6. Step 6: Final answer
    x = 98.40

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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.