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Finding the Fourth Proportional to 112.90, 155.70 and 81.70

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Solution

The fourth proportional to 112.90, 155.70 and 81.70 is: 112.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    112.90 : 155.70 = 81.70 : x
  2. Step 2: Convert to fraction form
    112.90/155.70 = 81.70/x
  3. Step 3: Cross multiply
    112.90x = 155.70 × 81.70
  4. Step 4: Simplify right side
    112.90x = 12,720.69
  5. Step 5: Solve for x
    x = 12,720.69/112.90
  6. Step 6: Final answer
    x = 112.67

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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.