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Finding the Fourth Proportional to 145.12, 199.89 and 121.78

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Solution

The fourth proportional to 145.12, 199.89 and 121.78 is: 167.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    145.12 : 199.89 = 121.78 : x
  2. Step 2: Convert to fraction form
    145.12/199.89 = 121.78/x
  3. Step 3: Cross multiply
    145.12x = 199.89 × 121.78
  4. Step 4: Simplify right side
    145.12x = 24,342.60
  5. Step 5: Solve for x
    x = 24,342.60/145.12
  6. Step 6: Final answer
    x = 167.74

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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.