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Finding the Fourth Proportional to 113.70, 156.81 and 72.21

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Solution

The fourth proportional to 113.70, 156.81 and 72.21 is: 99.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    113.70 : 156.81 = 72.21 : x
  2. Step 2: Convert to fraction form
    113.70/156.81 = 72.21/x
  3. Step 3: Cross multiply
    113.70x = 156.81 × 72.21
  4. Step 4: Simplify right side
    113.70x = 11,323.25
  5. Step 5: Solve for x
    x = 11,323.25/113.70
  6. Step 6: Final answer
    x = 99.59

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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.