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Finding the Fourth Proportional to 71.40, 106.38 and 66.78

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Solution

The fourth proportional to 71.40, 106.38 and 66.78 is: 99.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    71.40 : 106.38 = 66.78 : x
  2. Step 2: Convert to fraction form
    71.40/106.38 = 66.78/x
  3. Step 3: Cross multiply
    71.40x = 106.38 × 66.78
  4. Step 4: Simplify right side
    71.40x = 7,104.06
  5. Step 5: Solve for x
    x = 7,104.06/71.40
  6. Step 6: Final answer
    x = 99.50

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.