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Finding the Fourth Proportional to 209.89, 314.90 and 79.90

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Solution

The fourth proportional to 209.89, 314.90 and 79.90 is: 119.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.89 : 314.90 = 79.90 : x
  2. Step 2: Convert to fraction form
    209.89/314.90 = 79.90/x
  3. Step 3: Cross multiply
    209.89x = 314.90 × 79.90
  4. Step 4: Simplify right side
    209.89x = 25,160.51
  5. Step 5: Solve for x
    x = 25,160.51/209.89
  6. Step 6: Final answer
    x = 119.87

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.