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Finding the Fourth Proportional to 78.42, 117.70 and 66.41

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Solution

The fourth proportional to 78.42, 117.70 and 66.41 is: 99.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.42 : 117.70 = 66.41 : x
  2. Step 2: Convert to fraction form
    78.42/117.70 = 66.41/x
  3. Step 3: Cross multiply
    78.42x = 117.70 × 66.41
  4. Step 4: Simplify right side
    78.42x = 7,815.70
  5. Step 5: Solve for x
    x = 7,815.70/78.42
  6. Step 6: Final answer
    x = 99.66

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.