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Finding the Fourth Proportional to 1,138.20, 1,707.70 and 407.80

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Solution

The fourth proportional to 1,138.20, 1,707.70 and 407.80 is: 611.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,138.20 : 1,707.70 = 407.80 : x
  2. Step 2: Convert to fraction form
    1,138.20/1,707.70 = 407.80/x
  3. Step 3: Cross multiply
    1,138.20x = 1,707.70 × 407.80
  4. Step 4: Simplify right side
    1,138.20x = 696,400.06
  5. Step 5: Solve for x
    x = 696,400.06/1,138.20
  6. Step 6: Final answer
    x = 611.84

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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.