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Finding the Fourth Proportional to 156.40, 215.61 and 107.20

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Solution

The fourth proportional to 156.40, 215.61 and 107.20 is: 147.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    156.40 : 215.61 = 107.20 : x
  2. Step 2: Convert to fraction form
    156.40/215.61 = 107.20/x
  3. Step 3: Cross multiply
    156.40x = 215.61 × 107.20
  4. Step 4: Simplify right side
    156.40x = 23,113.39
  5. Step 5: Solve for x
    x = 23,113.39/156.40
  6. Step 6: Final answer
    x = 147.78

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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.