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Finding the Fourth Proportional to 187.19, 258.20 and 120.78

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Solution

The fourth proportional to 187.19, 258.20 and 120.78 is: 166.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    187.19 : 258.20 = 120.78 : x
  2. Step 2: Convert to fraction form
    187.19/258.20 = 120.78/x
  3. Step 3: Cross multiply
    187.19x = 258.20 × 120.78
  4. Step 4: Simplify right side
    187.19x = 31,185.40
  5. Step 5: Solve for x
    x = 31,185.40/187.19
  6. Step 6: Final answer
    x = 166.60

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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.