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Finding the Fourth Proportional to 139.71, 209.48 and 99.21

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Solution

The fourth proportional to 139.71, 209.48 and 99.21 is: 148.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.71 : 209.48 = 99.21 : x
  2. Step 2: Convert to fraction form
    139.71/209.48 = 99.21/x
  3. Step 3: Cross multiply
    139.71x = 209.48 × 99.21
  4. Step 4: Simplify right side
    139.71x = 20,782.01
  5. Step 5: Solve for x
    x = 20,782.01/139.71
  6. Step 6: Final answer
    x = 148.75

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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.