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Finding the Fourth Proportional to 119.86, 165.31 and 78.45

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Solution

The fourth proportional to 119.86, 165.31 and 78.45 is: 108.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    119.86 : 165.31 = 78.45 : x
  2. Step 2: Convert to fraction form
    119.86/165.31 = 78.45/x
  3. Step 3: Cross multiply
    119.86x = 165.31 × 78.45
  4. Step 4: Simplify right side
    119.86x = 12,968.57
  5. Step 5: Solve for x
    x = 12,968.57/119.86
  6. Step 6: Final answer
    x = 108.20

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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.