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Finding the Fourth Proportional to 128.47, 177.10 and 121.63

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Solution

The fourth proportional to 128.47, 177.10 and 121.63 is: 167.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.47 : 177.10 = 121.63 : x
  2. Step 2: Convert to fraction form
    128.47/177.10 = 121.63/x
  3. Step 3: Cross multiply
    128.47x = 177.10 × 121.63
  4. Step 4: Simplify right side
    128.47x = 21,540.67
  5. Step 5: Solve for x
    x = 21,540.67/128.47
  6. Step 6: Final answer
    x = 167.67

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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.