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Finding the Fourth Proportional to 121.39, 180.70 and 115.80

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Solution

The fourth proportional to 121.39, 180.70 and 115.80 is: 172.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.39 : 180.70 = 115.80 : x
  2. Step 2: Convert to fraction form
    121.39/180.70 = 115.80/x
  3. Step 3: Cross multiply
    121.39x = 180.70 × 115.80
  4. Step 4: Simplify right side
    121.39x = 20,925.06
  5. Step 5: Solve for x
    x = 20,925.06/121.39
  6. Step 6: Final answer
    x = 172.38

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.