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Finding the Fourth Proportional to 399.79, 599.69 and 139.78

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Solution

The fourth proportional to 399.79, 599.69 and 139.78 is: 209.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    399.79 : 599.69 = 139.78 : x
  2. Step 2: Convert to fraction form
    399.79/599.69 = 139.78/x
  3. Step 3: Cross multiply
    399.79x = 599.69 × 139.78
  4. Step 4: Simplify right side
    399.79x = 83,824.67
  5. Step 5: Solve for x
    x = 83,824.67/399.79
  6. Step 6: Final answer
    x = 209.67

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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.