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Finding the Fourth Proportional to 156.61, 216.36 and 121.78

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Solution

The fourth proportional to 156.61, 216.36 and 121.78 is: 168.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    156.61 : 216.36 = 121.78 : x
  2. Step 2: Convert to fraction form
    156.61/216.36 = 121.78/x
  3. Step 3: Cross multiply
    156.61x = 216.36 × 121.78
  4. Step 4: Simplify right side
    156.61x = 26,348.32
  5. Step 5: Solve for x
    x = 26,348.32/156.61
  6. Step 6: Final answer
    x = 168.24

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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.