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Finding the Fourth Proportional to 78.40, 118.14 and 65.85

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Solution

The fourth proportional to 78.40, 118.14 and 65.85 is: 99.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.40 : 118.14 = 65.85 : x
  2. Step 2: Convert to fraction form
    78.40/118.14 = 65.85/x
  3. Step 3: Cross multiply
    78.40x = 118.14 × 65.85
  4. Step 4: Simplify right side
    78.40x = 7,779.52
  5. Step 5: Solve for x
    x = 7,779.52/78.40
  6. Step 6: Final answer
    x = 99.23

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.