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Finding the Fourth Proportional to 156.76, 216.40 and 121.70

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Solution

The fourth proportional to 156.76, 216.40 and 121.70 is: 168.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    156.76 : 216.40 = 121.70 : x
  2. Step 2: Convert to fraction form
    156.76/216.40 = 121.70/x
  3. Step 3: Cross multiply
    156.76x = 216.40 × 121.70
  4. Step 4: Simplify right side
    156.76x = 26,335.88
  5. Step 5: Solve for x
    x = 26,335.88/156.76
  6. Step 6: Final answer
    x = 168.00

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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.