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Finding the Fourth Proportional to 105.45, 158.21 and 78.45

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Solution

The fourth proportional to 105.45, 158.21 and 78.45 is: 117.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    105.45 : 158.21 = 78.45 : x
  2. Step 2: Convert to fraction form
    105.45/158.21 = 78.45/x
  3. Step 3: Cross multiply
    105.45x = 158.21 × 78.45
  4. Step 4: Simplify right side
    105.45x = 12,411.57
  5. Step 5: Solve for x
    x = 12,411.57/105.45
  6. Step 6: Final answer
    x = 117.70

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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.