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Finding the Fourth Proportional to 209.80, 314.70 and 79.78

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Solution

The fourth proportional to 209.80, 314.70 and 79.78 is: 119.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.80 : 314.70 = 79.78 : x
  2. Step 2: Convert to fraction form
    209.80/314.70 = 79.78/x
  3. Step 3: Cross multiply
    209.80x = 314.70 × 79.78
  4. Step 4: Simplify right side
    209.80x = 25,106.77
  5. Step 5: Solve for x
    x = 25,106.77/209.80
  6. Step 6: Final answer
    x = 119.67

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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.